M. H. Klin et al., "2D-configurations and clique-cyclic orientations of the graphs L(K_p)", pages 149-162 of Reports in Molecular Theory, Vol. 1, 1990.
D. E. Knuth, ``Axioms and hulls,'' Lect. Notes Comp. Sci., Vol. 606.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).