Books on ethics are shelved in the library under the call number BJ. Particularly check the first-floor reference section for encylopedias on ethics.
Christian ethics and virtues are found primarily in the call number BV.
Ethics associated with a profession are generally shelved with works on that profession, in special topic areas
Search the library catalog if you have a specific topic in mind; for instance "relativism", "friendship", "faith", "accounting ethics", "student ethics", or the like.