The Blume Library offers access to resources that review tests & measures. The Mental Measurements Yearbook and PsycINFO are sources for reviews. The PsycINFO video, below, gives you tips for finding articles with tests or reviews of tests.
The Library does not have a collection of tests or access to PsycTESTS. So, it is likely you will have to either 1) contact the publisher and purchase the test or 2) contact the author for permission to use the instrument. This method may be the only way to use "unpublished" test.
Search the Discover for the terms like psychological tests, educational tests and measurements, or psychometrics to materials relating to tests and measurement. Limit to Monographs if you only want to see books.