Maurice Lecat. Bibliographie de la Relativité, suivie d'un appendice sur les déterminants à deux dimensions, le calcul des variations, les séries trigonométriques, et l'azéotropisme. Bruxelles, Lamertin, 1924. 292+47 pp. Nicely rebound in linen, with the original wrappers bound in. The 47 addition pages is the appendix "Bibliographie des Determinants a Plus de Deux Dimensions". Fine copy, wide-ish margins. $275
Lecat (also well known for his bibliography on the calculus of variations) produced this very useful ca. 4,000-entry tool in 1924, listing his entries alphabetically by author, (in two sections, with a smaller second section of additional material), alphabetically by publication (interesting!) and also chronologically (listed by single-line entries, cross-indexed, pp 208-282).
Additionally he provides this interesting graph on the output of relativity literature: