1. G. F. Laptev, “Separation of One Class of Intrinsic Geometries Induced on a Surface in an Affinely Connected Domain,” Sov. Phys. Dokl. 41(8), 329–331 (1943).
2. A. V. Stolyarov, “Dual Geometry of a Normalized Affinely Connected Space,” Vestn. Chuvashsk. Gos. Ped. Univ., No. 4, 21–27 (2005).
3. A. P. Norden, Affinely Connectted Spaces (Nauka, Moscow, 1976) [in Russian].
4. A. V. Stolyarov, Dual Theory of Framed Manifolds (Chuvashsk. Gos. Ped. Inst., Cheboksary, 1994) [in Russian].
5. P. K. Rashevskii, Riemann Geometry and Tensor Analysis (Nauka, Moscow, 1967) [in Russian].