While adding articles for other journals, I had largely been avoiding book reviews, since they were in a different format, and since Zotero seemed not to have a special category for them. But I see no need to deliberately leave them out. I guess they can just be added as "journal articles", along with some indication somewhere that they are  book  reviews (quite often this is indicated in the title, but not always). Does anyone else have an opinion on this? -- Chuck

How about adding [Review] oder [Rev.] in square brackets? 

Another option might be to put review entries as a note to the bibliographical entry to which they belong. 

Peter Wyzlic

Thanks for the feedback. I find it slightly annoying that Zotero has no 'book review' category in which one could enter review author etc. As it stands I think I'd go with putting 'review' in the title rather than as a biographical note. I see the reviews as independent entities -- with their own URLs etc -- so I wouldn't be too keen to attach them to other references. I hope that solution is fine with everyone.