Corbin on Contracts by A Treatise on the Law of Contracts (Williston) by Both Lexis and Westlaw have the Restatement of the Law of Contracts 2d in their collections of secondary sources. Westlaw also has the first series of the Restatement. Note that the format differs between Westlaw and Lexis, especially in regards to the case citations associated with the various Restatement sections.
Hein online has both series and a clear breakout of the various drafts which were produced in the process of promulgating the Restatements in its American Law Institute Library. You'll notice that Hein has scans of the print publications.
To use the print, you will need to consult the main volumes to read the rule of law, comments, illustrations and reporters notes. If you are seeking the case annotations, you will need to use the printed appendixes that accompany the main Restatement volumes and break down the case law by year and then by section. Cases are listed by court - federal before state and by highest to lowest jurisdiction. Users following caselaw spanning a number of years will need to consult multiple appendixes.
The GMU Law Library has the print Restatements on the second floor.
State contract law sources will vary by jurisdiction. Some states do have published guides in this area of law. Check all available resources, print and electronic, for access points. If there is no focused state guide on contract law, look for a state law encyclopedia or broad practice guide.
