Originally Posted by FlyerJosh

The FAR's (Federal Aviation Regulations), Part 61 was a very general listing of the knowledge and skill requirements. This is supplemented by the FAA Practical Test Standards, which has a listing of the knowledge and maneuvers you have to demonstrate on your checkride.

Beyond that, as mentioned previously there are several options for syllabi- some are commercially available for purchase such as ASA and Jeppesen, others you can find for free on the internet. Some are directly purchased from the flight school you are attending (they have their own in house syllabus).

To my knowledge, Jeppesen does not provide online or e-book versions of their textbooks.