Textbooks on the theory of relativity have been published by several notable physicists and mathematicians: The primary sources section of the latter article in particular contains many additional (early) publications of importance in the field.
Translation by George Barker Jeffery and Wilfrid Perrett in The Principle of Relativity, London: Methuen and Company, Ltd. (1923).
:Used the newly formulated theory of special relativity to introduce the mass energy formula.
In: The Principle of Relativity (1920), Calcutta: University Press, 1-69 ** Translation by Meghnad Saha, "Space and Time" (1920): Wikisource link.
:Used concepts developed in the then-current textbooks (e.g., vector analysis and non-Euclidean geometry) to provide entry into mathematical physics with a vector-based introduction to quaternions and a primer on matrix notation for linear transformations of 4-vectors.