One of my references is a book chapter. To add the reference in Zetero, I choose the reference type as book chapter, and can add the title and authors of the chapter, title of the book, publisher, ISBN, etc. However, I see no place to add the editors of the whole book. Am I overlooking something or using the wrong category?

PS: As I am using the Danish translation of Zetero (v. 4.0.29.10), the reference type is called "Bidrag til bog", which litterally means "Contribution to book". I take this to be the "Book chapter" in the English version.