Disability Rights California (the Protection and Advocacy, Inc - or PAI - of California) produces many great publications that are user friendly, readily available, and free. What is wonderful about their publications is that they are very "parent-friendly" and easy to understand.
DRC's Special Education Rights and Responsibilities Manual (commonly referred to as the "SERR Manual") is a comprehensive resource for parents and advocates on everything related to special education in California. Topics are covered in question and answer format, with a combination of both information and practical tips.
The SERR Manual is available for download at the following link: