If you're looking for a specific item, the best way to track it down is by using the university's  library catalogue, iDiscover:

Search for books and ebooks in 'Cambridge Libraries Collections'.

Type the author's name and a few key words into the search box.

If the book is available as an ebook (and many of them are) then you should be able to get to it directly by clicking 'Full text available'.

If it isn't online, then iDiscover will tell you where the print copies can be found.

Search for journal articles under 'Articles and Online Resources'.

You can also see the whole list of journals the university subscribes to on the University Library ejournals website. 

For print copies, remember that the catalogue includes records for all the many libraries in Cambridge so you will need to filter your search results by library. If the results still show records for 'Library x and other locations' , the Marshall Library is probably one of those other locations. Click on the link and keep 'clicking through' for more detailed information. Eventually you will be able to see a list of individual copies of a given book held by the library, and whether they are 'in place' (on the shelf) or out on loan.

For more detailed information about iDiscover and its functionality, there is a separate LibGuide available here:

Cambridge LibGuide to iDiscover