A tip somewhat related to Getting papers, google, NUS library:
Getting books from other NUS libraries delivered to the one nearest to you. (Intra Library Loan)

Browse to
http://libpweb.nus.edu.sg/web/appmanager/lib/desk

Log in and select E-Forms → Loan Services → Request to borrow books held in other NUS Libraries

Useful if you are lazy to make that trip to the Central or HSS Library.