What reference source would you use to find what language amnesia comes from?

To find the origin of the word "amnesia," you would use a etymology dictionary.

Here's why:

* Etymology is the study of the origin and history of words.

* Etymology dictionaries specialize in providing the historical development of words, including their origin language, changes in meaning, and related words.

Some popular etymology dictionaries include:

* The Oxford English Dictionary (OED)

* Merriam-Webster's Dictionary of English Usage

* Online Etymology Dictionary

By searching for "amnesia" in these resources, you would discover that it comes from the Greek word "amnesis," meaning "forgetfulness."