Raja Yoga

Yoga Sutras by patanjali - the science of Yoga, I.K. Taimni - a book review.
Yoga Sutras by Patanjali, translation and commentary by Ravi Ravindra. Book review.
Raja Yoga - Sri Swami Sivananda expounds on the philosophy of Yoga, the Sutras of Patanjali, and other aspects of Raja Yoga.
Raja Yoga of Shri Ramchadraji - Based on the philosophy and practice of Raja yoga as modified by Sri Ramchandraji Maharaj of Shajahanpur.
Sameeksha: Astanga Yoga - Provides brief history of Patanjali's eight-limbed path, along with information on asanas, pranayama, the teachings of Swami Vivekenanda, and many links to teachers and other resources.