no. 4
The coarseness of a graph
Compositio Mathematica, Tome 19 (1968) no. 4, pp. 290-298. 
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Beineke, Lowell W.; Chartrand, Gary. The coarseness of a graph. Compositio Mathematica, Tome 19 (1968) no. 4, pp. 290-298. http://archive.numdam.org/item/CM_1968__19_4_290_0/

L.W. Beineke [1] On the decomposition of complete graphs into planar and other subgraphs. Doctoral thesis, The University of Michigan, 1965.

K. Kuratowski [2] Sur le problème des courbes gauches en topologie. Fund. Math. 16 (1930), 271-283. | JFM

W.T. Tutte [3] The thickness of a graph. Indag. Math. 25 (1963), 567-577. | Zbl