1. Bejancu A and Farran H R, On the geometry of semi-Riemannian distributions, Anal. St. Univ. ‘Al. I. Cuza’ Isai, 51, s.l., f.1, (2005) 133–146
2. Bejancu A and Farran H R, Structural and transversal geometry of foliations, Int. J. Pure Appl. Math. 9(4) (2003) 419–450
3. Ianus S, Some almost product structures on manifolds with linear connections, Kodai Math. Sem. Rep. 23 (1971) 305–310
4. Kobayashi S and Nomizu K, Foundations of Differential Geometry (New York: Interscience) (1963) vol I
5. O’Neill B, Semi-Riemannian geometry with applications to relativity (New York: Academic Press) (1983)