Browsing the shelves for materials related to your topic can be a useful way to identify items that may be useful to you. If you find one or two items in the catalog that seem promising, look on the shelves at the items surrounding them. Be aware that some things, of course, may be checked out or otherwise not on the shelf, but this can still help you identify items quickly.

Classification [“class” or "call"] numbers for books and scores about string quartets and quintets are as follows:

Dewey classification: string quartets are at 787.044, and then filed alphabetically by composer. So, for example, 787.044 B39 might be string quartets by Beethoven. String quintets are to be found at 787.045 (and string sextets would be at 787.046, string septets at 787.047, and so on). Scores in the Dewey system would begin with M, (e.g.,  M787.044).

Library of Congress classification sequence: string quartets are at M452, then filed alphabetically by composer. So, for example, Beethoven’s string quartets will be at M452.B39. String quintets are to be found at M552; string sextets at M652; string septets at M752, and so on.

If you want parts, rather than just a score, include “and parts” in your search. For example:

   Brahms string quartets parts

Usually string quintets are for 2 violins, viola, and cello. But string quintets can include either 2 cellos or 2 violas. If you know that you want repertoire for the 2 violins/2 violas/cello combination, you search:

   quintets strings “violas (2)” parts

   or

   “String quintets” “violas (2)” parts

This information is stored in the subject field of the item's record in the catalog, and you can in fact search just that field instead of doing a keyword search to be more precise. This looks like:

In a record for an item it looks like this (the display says "Topics" instead of "Subject".

You can use any of the above tricks both in the UIUC catalog; in the iShare catalog; and in WorldCat.