[1] M. A. Arbib: Automata Theory and Control Theory - A rapprochement. Automatica 3 (1966), pp. 161-189. DOI 10.1016/0005-1098(66)90011-2 | Zbl 0141.28402

[2] M. A. Arbib: Tolerance Automata. Kybernetica 3 (1967), pp. 223-233. MR 0223185 | Zbl 0153.01201

[3] T. Poston: Fuzzy Geometry. Thesis. Univ. of Warwick (1971).

[4] E. C. Zeeman: The topology of the brain and visual perception. In: The Topology of $3$-manifolds. Ed. Fort, Prentice-Hall (1961), pp. 240-256. MR 0140374

[5] E. С. Zeeman O. P. Buneman: Tolerance spaces and the brain. In: Towards a Theoretical Biology. Vol. 1 ed Waddington (1968), pp. 140-151.

[6] B. Zelinka: Tolerance relations on algebraic structures I. Czech. Math. Journal 20 (1970), pp. 179-183. MR 0260653