Lewis F. Richardson, The problem of contiguity: An appendix to Statistics of Deadly Quarrels, in General Systems: Yearbook of the Society for the Advancement of General Systems Theory., vol. 6, n. 139, Society for General Systems Research, 1961, pp. 139–187, ISSN 0072-0798 (WC · ACNP).
«In the previous section integrals were taken around simple geometrical figures, as a preliminary to taking them around frontiers shown on political maps. An embarrassing doubt arose as to whether actual frontiers were so intricate as to invalidate that otherwise promising theory. A special investigation was made to settle this question. Some strange features came to notice; nevertheless an over-all general correction was found possible. The results will now be reported. ... As an explanation of how chance can arise in a world which he regarded as strictly deterministic, Heri Poincare* (no date) drew attention to insignificant causes which produced very noticeable effects. Sea coasts provide an apt illustration.»
