As a simple Google search will reveal, there a number of quality guides addressing free and low cost legal research sources. Some of these sources are linked below and can serve as additional resources. This guide does not attempt to address all possible sources available for legal research; rather, this guide is meant to address the resources available for South Dakota attorneys.
Georgetown Law Library - Free and Low Cost Legal Research Guide
Harvard Law School Library - Alternate Legal Research Tools
Indiana University Bloomington, Jerome Hall Law Library - Free and Low-Cost Legal Research
Pace Law School Library - Free and Low Cost Resources for Legal Research