1. J. Am. Chem. Soc. 110 (1988), in press.
2. Conformational analysis. 130. MM2. A hydrocarbon force field utilizing V1 and V2 torsional terms
3. A referee has kindly drawn our attention to theoretical structural studies of W. Fischer on interpenetrating tetragonal sphere packings of low density, in particular three- and fivefold interpenetration patterns in space group I41/ a: Habilitationsschrift, Universit�t Marburg 1970, pp. 40f, 138ff; compare also: