Composite References

Several journals (mainly Chemisty and related) prefer composite references over normal ones:
normal [1-6]

composite [1]
[1] a) ... f)

Endnote is able to do this since 2009 but I didn't find this feature for Zotero.
Is there a chance that this will be possible soon? Or is this already possible?
  • Can you provide an author/submissions guide for one such journal so we can see exactly what this should look like? Also post some complete references of this sort here as well.
  • Journals are e.g. 'Small' or 'Chemistry - A European Journal' (Wiley)
    guidlines from small:
    paper from small:

    guidlines from "Chemisty - A European Journal"
    Paper from chemistry:

    Does this input help?
  • That does help.

    So we need to do something like
    [1] a) B. M. Trost, Chem. Eur. J. 1998, 4, 2405–2412; b) H. J. Ache, Angew. Chem. 1989, 101, 1–21; Angew. Chem. Int. Ed. Engl. 1989, 28, 1–20; c) H. Frey, Angew. Chem. 1998, 110, 2313–2318; Angew. Chem. Int. Ed. 1998, 37, 2193–2197.
    I'm afraid that this isn't yet possible, but hopefully one of our CSL gurus can confirm that. If this is indeed not currently possible, it probably won't happen for some time, since I don't see mention of such behavior in the CSL 1.0 specification, and I don't think that CSL 1.1 has even been started.

    But maybe another of the style requirements, standard journal abbreviations, will also make it into the CSL 1.1 standard, so at least those two birds will be hit by a single stone, even if that stone is relatively far off.

    If this isn't possible now, we'll want as large as possible a listing of journals that require this and similar behavior, to justify and correctly develop such a feature for a future release. Can you survey journals in your field to create such a list?
  • Begin my standard rant:

    WTF are these editors thinking?!!!!

    We haven't designed this feature in, because, frankly, we had no reasonable expectation to ever see it. But never underestimate the capacity for people to reinvent the wheel and make things difficult for everyone else.

    So if I understand right, every citation group gets a number, and every item within each group gets a letter index?

    What happens if it's just a single reference citation?
  • Yes, you understand right.
    A single reference will also get a number (like a group) but in the bibliography it won't have a letter index. like this:

    [4] a) J. S. Lee, P. A. Ulmann, M. S. Han, C. A. Mirkin, Nano Lett. 2008, 8,
    529–533; b) Z. S. Wu, S. B. Zhang, M. M. Guo, C. R. Chen,
    G. L. Shen, R. Q. Yu, Anal. Chim. Acta 2007, 584, 122–128;
    c) F. X. Zhang, L. Han, L. B. Israel, J. G. Daras, M. M. Maye,
    N. K. Ly, C. J. Zhong, Analyst 2002, 127, 462–465.
    [5] S. Chah, M. R. Hammond, R. N. Zare, Chem. Biol. 2005, 12, 323–
  • Single reference citation:
    [3] E. Wingender, Gene Regulation in Eukaryotes, VCH, Weinheim, 1993, p. 215.

    I don't think this is that off-the-wall of a requirement-- think of it as more like numbered footnotes, and each footnote can contain one or more references. Some styles would simply delimit them by semicolons; this style gives them indices. It'll be important here to figure out if this is just an idiosyncrasy of these two journals, or whether this is common in a certain academic tradition, so a list of relevant style guides/journals is important.
  • I will search for more journals that prefer this kind of citing and supply a list ...
  • I don't think this is that off-the-wall of a requirement-- think of it as more like numbered footnotes, and each footnote can contain one or more references.
    In a vaccuum, perhaps not.

    But in the context of the real world of actually existing software code and thousands of existing citation styles, It absolutely is an "off-the-wall requirement."

    And yes, some additional research would be really helpful, so that we implement this correctly, and so some other trivial variation doesn't later require further changes in CSL.
  • I can confirm that this is, unfortunately, quite common. It has come up a bunch of times as I have coded styles in the sciences and engineering. While I agree it's a terrible idea, it probably is something that csl should be able to do.
  • So as long as we can separately index and print citation group and citation item, we should be set; right?
  • Yes, I think so.
  • This style of composite is represented in many journals. Even if the journal prefers this, about half of the papers are in standard style.
    I found composite references in the following journals (but I do not know which journals actually prefer it):
    Material Letter (without letters in bibliography)
    Materials and Chemistry Physics
    Angew. Chem. Int. Ed.
    Journal of Organic Chemistry
    Journal of organometallic chemistry
    tetrahedron letters
    Asymmetric synthesis
    Chem Comm
    Dyes and Pigments
    Eur. J. Org. Chem
    Small Chemistry - A European Journal

    ... then I stopped searching ;-)
  • And they all do them in the same way? Are references sorted within the compound reference? Is ibid or some other form of shortening used?

    But the list confirms that organic chemists and chemists in general, at least in Europe, like this style.
  • edited November 9, 2010
    My first reaction to this was, "oh ... forget it."

    On the homeward commute last night, though, I thought it through a bit, and it might not be that hard to implement in the processor (with appropriate extensions to the CSL language), depending on the rules imposed by the style. It depends on how the edge cases are meant to be handled.

    Further questions ...

    Can in-text backreferences target individual items within a group? (i.e. "I am an atom. [3a]")

    If so, do in-text backreferences collapse on the "group" number. Do they do ranged collapsing on the "subitem" number? If collapsing is used, is a backreference to all members of a group containing multiple items made to the group as a whole (just the "group" number) or to the items individually ("group" number and "subitem" number for each)? (i.e. "I am a molecule. [1a,c;4b-d;7]")

    Assuming that in-text backreferences to individual items are used, how are cross-nested items handled in-text and in the bibliography? That is, if citation cluster [1] contains three items A, B and C -- as 1(a), 1(b) and 1(c) -- and citation cluster [2] contains items B, D and F, how is the second item B reference shown, in-text and (harder) in the bibliography? I can think of many possibilities ... do the styles apply consistent rules/conventions to this case, and what are they?
  • From the PDF preprint provided above:
    Furthermore, the 1:2 stoi-
    chiometry of the formed complex was verified by a Job
    plot[41] (Figure 16 in the Supporting Information), and the
    shape of the actual Job curve, which is known to depend on
    the complex stability in a characteristic manner,[41c] was in
    excellent agreement with the stability constant of 108 mÀ2 de-
    rived from the ITC measurements.

    [41]a) P. Job, Ann. Chim. 1928, 9, 113 – 203; b) C. Y. Huang, Methods
    Enzymol. 1982, 87, 509 – 525; c) L. Sommer, M. Langovμ, Crit. Rev.
    Anal. Chem. 1988, 19, 225 – 269.

    And the last sentence:
    This should lead to improved properties in supramolecular
    polymeric materials,[1b, 45] as the self-healing is accelerated.

    [1] Original work: a) G. T. Morgan, F. H. Burstall, J. Chem. Soc. 1932,
    20 – 30. A comprehensive treatment is given in: b) U. S. Schubert, H.
    Hofmeier, G. R. Newkome in Modern Terpyridine Chemistry, Wiley-
    VCH, Weinheim, 2006.
    [45] a) T. Nakano, Y. Okamoto, Chem. Rev. 2001, 101, 4013 – 4038;
    b) J. J. L. M. Cornelissen, A. E. Rowan, R. J. M. Nolte, N. A. J. M.
    Sommerdijk, Chem. Rev. 2001, 101, 4039 – 4070.

    Thus, it appears that we have backreferencing to subitems, endnotes, and no separate bibliography.
  • edited November 9, 2010
    The problem is that the composition of the in-text backreference numbers (the superscripted numbers in the text) is governed by the sequence and organization of the refs in the endnotes section. The word processors can't handle that, so we would need to define this as an in-text style, and render the endnotes as a CSL bibliography.
  • So am I understanding that the details of this case are so complicated that, if implemented, it would force the processor to create fake endnotes just to be able to represent it?

    If yes, then this would suggest it's too complicated to bother. I seriously doubt that "Endnote is able to do [all of] this since 2009," as jens suggested in the OP.
  • no. The processor would just treat this like any other numeric style - which it is. The only two differences would be that
    1. Multiple citations wouldn't be 4-6 but just 4
    2. In the Bibliography they would be displayed as 4a b c
    That doesn't seem to terrible?
  • @adamsmith--
    No, we need to use things like [1b,45] in-text. As Frank points out, word processors don't let us create customized indices for endnotes, or at least the current plugins can't.
  • edited November 9, 2010
    The [1b,45] case really is where the need for special handling comes to the surface. The Zotero citation that generates this might contain (say) four items, one of which (somewhere among the four) has been previously cited, and (say) three of which are cited for the first time in this citation.

    In the bibliography, the "45" group would in that case contain only three items, and not the full set of four contained in the Zotero citation (at least that's how I understand it from the evidence so far). As a result of that "filtering", there would never be any backreferences in the endnotes/bibliography section -- which makes it more like a bibliography listing than a run of endnotes.
  • that's what I meant, I think. Aren't all numeric styles (by which I mean Nature, NLM, IEEE etc.) just in-text styles? There doesn't seem to be something extraordinary about the citation - I'm much more concerned about the bibliography.
  • Hi,
    Is there a chance that CSL could evolve to handle composite references?
    Many thanks,
  • A chance, yes, but it's not going to be soon.
  • @flamerie1, which journal do you need composite references for?
  • edited January 18, 2016
    I am a chemist and require the use of composite references for every major chemistry journal. Here is a list of examples, just off the top of my head:

    - Journal of the American Chemical Society
    - Organic Letters
    - Journal of Organic Chemistry
    - Chemical Reviews
    - ACS Catalysis
    - Chemical Communications
    - Green Chemistry
    - Org. Biomol. Chem.
    - Chemical Science
    - ChemBioChem
    - Angewandte Chemie
    - Angewandte Chemie International Edition
    - Advanced Synthesis & Catalysis
    - Chem. Soc. Rev.
    - ChemCatChem
    - Chemistry - An Asian Journal
    - Canadian Journal of Chemistry
    - Chemical Letters
    - Australian Journal of Chemistry
    - RSC Advances
    - Synthesis
    - Coordination Chemistry Reviews
    - Dalton Transactions
    - Synlett
    - Org. Proc. Res. Dev.
    - Journal of Molecular Catalysis: A
    - Acta Crystalographica
    - Tetrahedron
    - Tetrahedron Letters
    - Tetrahedron: Asymmetry
    - Organometallics
    - J. Med. Chem. Lett.
    - ChemMedChem
    - ChemPhysChem
    - New Journal of Chemistry
    - Natural Product Reports
    - Organic Chemistry Frontiers
    - Inorganic Chemistry Frontiers
    - Catalysis Science & Technology
    - ChemSusChem
    - Journal of Organometallic Chemistry
    - European Journal of Organic Chemistry
    - Inorganic Chemistry
    - Journal of Physical Chemistry A
    - Journal of Physical Chemistry B
    - Journal of Physical Chemistry C
    - European Journal of Inorganic Chemistry
    - Asian Journal of Organic Chemistry
    - European Journal of Inorganic Chemistry
    - Journal of Medicinal Chemistry
    - Langmuir
    - Molecules
    - Beilstein Journal of Organic Chemistry
    - Arkivoc
    - Journal of Fluorine Chemistry

    ... and many, many others.

    I promise you, I came up with that list from memory - they all use composite references. These are not obscure publications, either. They cover the spine of the literature in organic and inorganic chemistry (and there are probably many others from physical and materials chemistry which I didn't mention). Composite references are used across the major publishers also. It's not a European thing, as someone suggested above, it's international. It's used by the ACS, RSC, Wiley, Springer, Thieme, Elsevier and other publishers.

    EndNote can handle composite references, which testifies to the importance of this way of doing things.

    There is probably some difference in how the value of composite references is perceived between people from different backgrounds. However, in chemistry it is enormously logical to use it because it allows many references to be grouped by topic, for example in writing succinct introductions, or referring to multiple works by a single author/research group.

    This feature is the only thing that stands between me and a move from EndNote to Zotero, and it has done for over five years. It's probably the same thing for innumerable other chemists (I suspect quite a few thousand), who would prefer to use Zotero's otherwise fantastic feature set over EndNote's expensive version.

    Please, please, please develop this feature.

  • edited January 17, 2016
    We know they're used in all of chemistry. But here's the thing: these styles are widely used in exactly one discipline: Chemistry. They're not used by anyone else and they follow a logic that's a) still a bit unclear to us and b) is systematically different from every other citation style in every other discipline in the world (all of which follow a one-citation-per-citation-marker rule).

    The CSL language is developed and maintained entirely by volunteers as are the processors turning CSL into citations. So essentially this requires us to put in a ton of unpaid hours for something we understand poorly and none of us is personally affected by. The only other discipline with comparably unusual citation rules are lawyers, and we have one who spends countless hours working on that.
    Still, we are generally interested in seeing this happen, but it's not going to be soon unless someone mobilizes resources from inside chemistry -- either in terms of funds or in terms of developer-power -- to drive it forward.
    As things stand now, the actual rules for these are, to the best of my knowledge, not even documented anywhere in all their specifics (I know of the ACS style guide but I don't see a clear explanation there, for example, of how the grouping works, how subsequent citations to such groups work etc.).

    So "rules" are fairly simple for these types of references. I found the above discussion about this overly complex. Here is how it works.

    If you are writing with composite references enabled (e.g. in EndNote), then this happens:

    Imagine you are writing an introduction three sentences long. Something that would ordinarily (for non-chemists) look like:


    "The construction of C-C bonds is an important area of chemistry.[1-3] The Suzuki-Miyaura reaction ranks amongst the most important catalytic processes for this purpose.[4] To date, various mechanistic rationales for this reaction has been proposed.[5-6]"




    Note that references 1,2 and 3 as well as 5,6 are inserted grouped together, hence the ranges but these appear separate in the Bibliography (or References) section. When in Endnote I insert a reference and then another directly afterwards (or select two to insert at the same time), they are grouped.

    For a chemist writing with the composite references option, the reference manager would make it look like this:


    "The construction of C-C bonds is an important area of chemistry.[1] The Suzuki-Miyaura reaction ranks amongst the most important catalytic processes for this purpose.[2] To date, various mechanistic rationales for this reaction has been proposed.[3]"


    1. a)..., b)..., c)...
    3. a)..., b)...


    The order in which the references are grouped together as a) b) and c) in each composite reference is simply determined by the order in which they were added to the text. EndNote allows the user to "enter" each reference (e.g. by clicking on "[1]") and re-order the references as to which is a) and which is b).

    That's it.

    You can imagine a further theoretical "complication". Imagine a fourth reference is written. This should be able to borrow the numbering from the previous references. E.g.

    "Various calculations have been performed to investigate such reactions."[1b-c, 3b]

    References do not have to be grouped by author, or be ordered within the group by year. They are ordered the way they are put in.

    That's all there is to it. It is perhaps why the "rules" aren't documented. They are simple and generally quite intuitive, the ordering is arbitrary and up to the author to choose.



    I completely understand that making such a program highly functional is a great effort on the part of the participants and that resources are scant.

    That notwithstanding, this way of citing is far from rare if you consider that chemists number in the hundreds of thousands. Moreover, chemistry is the central science, and therefore this citation style spills over to journals that are, effectively, physical or biological in the topics they cover. So Zotero has a massive blind spot right in the centre of science.

    Finally, it seems to me that in undertaking the creation of something like Zotero, there should be some awareness of such citation styles long before any code is written. We are talking here about a style of output that orders text in a particular way, and which can be seen clearly in virtually every chemical, biochemical, materials, theoretical and physical chemistry journal (probably well over 150 journals). From the discussions above it seems to me that one objection is that the actual "engine room" of the software doesn't permit sufficient flexibility to make this happen. That seems a bizarre limitation in 2016, not least since other software (EndNote for example) has managed this a long time ago, as someone already noted.

    I understand it takes lots of effort and I am a chemist, not a programmer. But at the same time, it is a question of ordering text for a program whose function is to order text. In 2016.
  • [I]t seems to me that in undertaking the creation of something like Zotero, there should be some awareness of such citation styles long before any code is written.
    This raises a smile, but it doesn't bring us any closer to supporting composite styles.

    We need input from a chemist who knows this family of styles well, who is sympathetic to the need to get programming details right for all cases that the processor will encounter, and who understands that both the CSL language and the citeproc-js implementation of it are volunteer efforts.

    I'm sure that someone will come forward eventually. It's just a matter of time.
  • @lavoisier, if you're interested, you could certainly create some momentum by helping us determine how exactly these styles work, and what kind of variants exist. There are a bunch of additional questions that need answering beyond the information you gave above. I'd be happy to take care of the "engine room" end of things, so no programming experience required on your part.
  • Hi everyone,

    as a chemist, former Endnote and current Zotero user, I'd like to say that I have NEVER EVER EVER used composite references in my manuscripts submitted to ACS, Wiley or RSC. I've never had any comments about this from the editors, and the people in charge of page layout have never changed my references into composite ones. So I really don't think it's that big a deal.

    Now I am totally aware that matters of bibliographic format are not exactly a rational issue (I mean, why do we need so many styles). There are questions of taste, tradition, and so on, which I respect. I have some knowledge of Javascript and CSL, perhaps I will find the time to take a look.
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