The main shelfmarks for bioinformatics books include -
QU 26.5 - Informatics. Automatic data processing. Computers (General)
QU 58 - Nucleic acids and derivatives
Other books relating to bioinformatics are also be held off-site. These can be ordered through the SOLO library catalogue.
SOLO is Oxford University's library catalogue. You can use it to find both print and electronic material held in collections across the University.
You can search by Author, Title or Subject and limit to the Radcliffe Science Library (RSL). You can also use SOLO to order off-site material, check your library account and renew your books online.
Here's a Guide to using SOLO.
Examples of Bioinformatics books available at the Radcliffe Science Library. You can find many more by searching the SOLO catalogue.