Perhaps you should try some spelling variations:
"computer / operating systems / unit. / bisacsh" » "computer / operations systems / unit. / bisacsh", "computer / operation systems / unit. / bisacsh", "computer / operating systems / uni. / bisacsh"
"computer / operating systems / univ. / bisacsh" » "computer / operations systems / univ. / bisacsh", "computer / operation systems / univ. / bisacsh", "computer / operating systems / uni. / bisacsh"

Try widening your search to All Fields.

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: (("computer / operating systems / unit. / bisacsh") OR ("computer / operating systems / univ. / bisacsh")).
• Removing quotes may allow a broader search: (( computer / operating systems / unit. / bisacsh ) or ( computer / operating systems / univ. / bisacsh )).
• Adding a wildcard symbol may retrieve word variants: (("computer / operating systems / unit. / bisacsh") or ("computer / operating systems / univ. / bisacsh"))*.