BOGOLYUBOV, N. N.; PRYKARPATSKY, A. K. Generalized de Rham-Hodge complexes, the related characteristic Chern classes, and some applications to integrable multidimensional differential systems on Riemannian manifolds. Ukrains’kyi Matematychnyi Zhurnal, v. 59, n. 3, p. 327–344, 25 Mar. 2007.