‎"CARTAN, ÉLIE. - THE EINSTEIN-CARTAN THEORY (ECT) OF GRAVITATION.‎
‎Sur une définition géométrique du tenseur d'énergie d'Einstein. (+) Sur une généralisation de la notion de courbure de Riemann et les espaces à torsion. (+) Sur les espaces généralisés et la théorie de la Relativité. (+) Sur les espaces conformes...‎

‎Paris, Gauthier-Villars, 1922. 4to. Bound in 2 uniform full cloth, but of slightly different sizes. Paperlabels pasted to lower part of spines. A faint stamp to titlepage and some of the issues. In ""Comptes Rendus Hebdomadaires des Séances de L'Academie des Sciences"", Tome 174. 1815,(1) pp. (Entire volume offered). Cartan's papers: pp.437-439, 593-595, 734-737, 857-60, 1104-1107.‎

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‎First edition of these papers, in which Cartan intruced the concept of ""Torsion"", the main inspiration for Einstein in his searce for a unified field theory. The ECT of gravity is a modification of the General relativity Theory""The Einstein-Cartan theory, also known as the Einstein-Cartan-Sciama-Kibble theory, is a classical theory of gravitation similar to general relativity but relaxing the assumption that the affine connection has vanishing antisymmetric part (torsion tensor), so that the torsion can be coupled to the intrinsic angular momentum (spin) of matter, much in the same way in which the curvature is coupled to the energy and momentum of matter. In fact, the spin of matter in curved spacetime requires that torsion is not constrained to be zero but is a variable in the principle of stationary action. Regarding the metric and torsion tensors as independent variables gives the correct generalization of the conservation law for the total (orbital plus intrinsic) angular momentum to the presence of the gravitational field. The theory was first proposed by Élie Cartan in 1922 and expounded in the following few years. Dennis Sciama and Tom Kibble independently revisited the theory in the 1960s, and an important review was published in 1976. Albert Einstein became affiliated with the theory in 1928 during his unsuccessful attempt to match torsion to the electromagnetic field tensor as part of a unified field theory. This line of thought led him to the related but different theory of teleparallelism."" (Wikipedia).‎