There are a variety of useful immigration law research guides on the Internet that provide an overview of primary and secondary sources used for immigration law research - statutes, cases, secondary sources, regulations, agency decisions, and guidance documents.
This means that it is not necessary to remember everything yourself.
You can always find one by Googling something like: immigration law research guide
Georgetown Law Library Immigration Law (U.S.) Research Guide Example
Sometimes an easy way to start your research is to go to a agency's website since they usually link to their own primary sources such as statutes, regulations, decisions, etc.
Department of Justice Executive Office for Immigration Review
