What is your need?
Most often in America (and common law countries) you will need to find case law
Unless you are looking for a specific case (i.e. Brown v. Board) or statute (i.e. 14th Amendment), reading Law Review articles can provide a more comprehensive understanding of a topic (i.e. segregation).
In America courts create laws by interpreting prior cases and statutes (laws passed by legislative bodies). Case law comes from the courts, ranging from state lower courts all the way to the U.S. Supreme Court.
Beginning in Law School, legal scholars and lawyers will publish articles on topics in law reviews. These will often explore thelegal context of the topic by citing relevant legal decisions and statutes.
Prestigious law reviews often correlate to the top ranked law schools or State Bars. Law Schools often publish multiple law reviews, many are focused on specific topics in the law.
These are laws passed by legislative bodies, such as the U.S. Congress or a state's legislative branch.
Statutes are often compiled into code books.