Riddle of the Sphinx

Gameboomers: Riddle of the Sphinx Walkthrough
Detailed walkthrough including screenshots of puzzle solutions.
http://www.gameboomers.com/wtcheats/pcRr/riddleofthesphinx.html

MobyGames: Riddle of the Sphinx
Description, credits, release information, cover art, screenshots, reader reviews, and technical specifications.
http://www.mobygames.com/game/sheet/gameId=2801/

The Non-Boring Riddle of the Sphinx Walkthrough
Emphasis on reducing tedium, not divulging puzzle solutions.
http://www.geocities.com/ataniel/sphinx2.htm

Riddle of the Sphinx
Official site offers a demo, game patches, screenshots, and RotS-related wallpaper.
http://www.riddleofthesphinx.com/

Universal Hint System
Offers specific questions and hints in progressively detailed steps.
http://www.uhs-hints.com/uhsweb/rots.php