1. 1.a D. L. McKay, U.S. Pat. 4031,002, 1977
2. 1.b H. W. Mark, B. J. Bertus, J. S. Roberts and D. L. McKay, U.S. Pat. 4459,366, 1984
3. 1.c M. W. Blaschke and R. F. Miller, J. Link U.S. Pat. 4609,747 1986.
4. Inorganic stereochemistry
5. The valence-shell electron-pair repulsion (VSEPR) theory of directed valency