The 2010 ADA Standards for Accessible Design can be found at: http://www.ada.gov/2010ADAstandards_index.htm.
The Department of Justice’s ADA web site, www.ada.gov, contains a number of useful documents on accessibility for businesses and state and local governments. For example, for businesses see “ADA Update: A Primer for Small Business” and the section on “Making the Built Environment More Accessible” at: http://www.ada.gov/regs2010/smallbusiness/smallbusprimer2010.htm.
The U.S. Access Board also produces a number of documents on a wide range of accessibility-related topics which can be found at: www.access-board.gov. For example, check “Guide to Updated ADA Standards” at: http://web.archive.org/web/20130721160340/http://access-board.gov//ada/guide.htm.