Yogi Ramacharaka 
Raja Yoga [EPUB ebook] 

Each branch of Yoga is but a path leading towards unfoldment, development, and growth. What is known as Raja Yoga deals with the Mind, its control, its development. He who wants to develop his will-power and mental faculties, unfolding the inner senses, and latent powers, follows the path of Raja Yoga. Raja Yoga is known by many names and is often referred to as royal yoga, royal union, sahaj marg, classical yoga, and ashtanga yoga.