Statutes, Regulations, Practice Manuals, Etc
The statutes that govern US Immigration law (primarily the INA and USC). 
The regulations that govern Immigration Court (8 CFR).
The USCIS and EOIR Practice Manuals, Policy Memorandum, and other such materials.

Immigration Law Statutes
Immigration and Nationality Act (INA)

The INA is a main source of immigration law in the United States. It contains many of the most important provisions of law relevant to immigration proceedings.

Title 8 of the Code of Federal Regulations (CFR)

Title 8 of the CFR codifies the INA and includes regulations followed by the Department of Homeland Security and EOIR. The regulations cover practice and procedure in immigration proceedings.

Other Resources for Research

Country Condition Pages