I have a book series consisting of 4 parts, the first part was published in 1938 and the last part in 1940. The issue date of the series is therefor a date range. And I would like to enter it in Zotero as: 1938-1940. What is the CSL for this? According to the CSL 1.0.2 Specification the range-delimiter for the date-part should be available for this. But it isn't.

My research so far: Zotero parses 1938-1940 in

"issued": {
"date-parts": [
[
"1938"
]
],
"season": "1940"
}

Where this should be:

"issued": {
"date-parts": [
[
"1938"
],
[
"1940"
]
]
}