Each state's LLC and LLP laws are published in the state's statutes, which is of course available in hard copy and many electronic sources (see "State Statues"). In addition, each state's laws are published, with commentary and forms, in Bamberger and Basile's State Limited Partnership Laws.
Lubaroff & Altman on Delaware Limited Partnerships is the classic treatise on the subject.
Uniform Laws Annotated reprints the Uniform Partnership Act and the Limited Partnership Company Act with annotations and state variations.