Generally, sources provide descriptions but not the actual test instruments. Journal articles may include a portion or example of a test instrument. You might located the actual test instrument by:
Note: You need the copyright holder's permission to use the test if you plan to publish your research.
PsyArticles - In advance search, select TM Test & Measures as the search field. This field captures the tests and measures used in research study. It may be in the body or with an Appended label: Tests and Measures: Quest Atlantis Commitment Questionnaire (Appended)
CINAHL Plus - In advance search, select Instrumentation as the search field.
For other databases, search for your topic AND Test & Measures as the Subject search term. Look for alternate subjects such as inventory, questionnaire, assessments, or rating.
For reviews of tests, see Mental Measurements Yearbooks and Tests in Print.
Other books may be available that are specific to a discipline.