Remember, if a work is in the public domain, or if the use of a work is a fair use, permission need not be sought for the use of a copyrighted work.
Search the Stanford Copyright Renewal Database to see if a book published between 1923 - 1963 is still covered by copyright.
If in doubt, seek permission!
It is possible to write a letter to a copyright holder detailing how you would like to use their work. Permission may be granted for free, for a small or exorbitant fee, or declined. If permission is declined, it is best to seek out similar resources for your purposes.
The Copyright Clearance Center (CCC) issues fees for permission to use copyrighted works. Fees differ for course packs, classroom handouts, library reserves, and course management systems. If the copyright holder is in the CCC database, permission is automatically granted for usage when an order is completed. If the copyright holder is not in the database, CCC will seek permission on your behalf.