In 1969 Springer published the first edition of his Essential Relativity: Special, General, and Cosmological. The undergraduate textbook was lauded as a "refreshingly modern approach to the critical problem of teaching relativity theory." Another reviewer said it is "simply the best introduction" and is "filled with fabulous insights." When the second edition appeared in 1977 a reviewer noted its treatment "reminiscent of Mach's celebrated examination of the foundations of classical mechanics". On the other hand, the second edition "gives the barest hints of new developments" (models of neutron stars, in X-ray astronomy, supernova explosions, and quasars). Later, another reviewer criticized it for the paucity of diagrams, but lauded the chapter on cosmology as "lyrical, philosophical, yet technical."