Bibcode:1997JChEd..74..771S. doi:10.1021/ed074p771. CS1 maint: Uses authors parameter (link) ↑ or example, the Spartan program from Wavefunction, Inc. ↑ Warren J. Hehre, Alan J. Shusterman, Janet E. Nelson (1998). The Molecular Modeling Workbook for Organic Chemistry.