[1] E. ČECH: Topological spaces. (2nd edition, Prague, in preparation).

[2] C. H. DOWKER: Mappings of proximity structures. Gen. Top. and its Rel. to Mod. Anal. and Alg. (1962, Prague), 139-141. MR 0146792 | Zbl 0114.14101

[3] M. HUŠEK: S-categories. CMUC 5, 1 (1964), 37-46. MR 0174027

[4] M. HUŠEK: Generalized proximity and uniform spaces I. CMUC 5, 4 (1964), 247-266. MR 0176441