Balaban, A. T., C. C. Rentia, et al. (1968). "Chemical graphs. VI. Estimation of the relative stability of several planar and tridimensional lattices for elementary carbon." Rev. Roum. Chim. 13: 231-247.

Graphs of the orders 2, 3, and 4 were analyzed, considering planar networks analogous to the graphite network: 3 semiregular tesselations composed of quadrangles and octagons; triangles and dodecagons; and quadrangles, hexagons, and dodecagons, as well as irregular periodic networks composed of pentagons and heptagons. Conjugation energies and steric strain in these networks were calcd. Threedimensional lattices analogous to the diamond lattice were examd., and the energy of the truncated octahedral lattice was estd. Theoretical evidence is presented regarding the possibility of >3 forms of C, at least as local zones of imperfect graphite or diamond lattices.