1. M. G. Veselov (ed.), Modern Problems of Quantum Chemistry. Molecular Structure and Properties [in Russian], Nauka, Leningrad (1986).
2. F. Gill, U. Murray, and M. Reit, Practical Optimization, Academic Press, New York (1982).
3. R. D. Amos, ?Structure and harmonic vibrational frequencies of the carbon suboxide molecule using analytic derivative methods,? Chem. Phys. Lett., 108, No. 4, 347?352 (1984).
4. P. Pulay, ?Ab initio calculation on force constants and equilibrium geometries in polyatomic molecules. 1. Theory,? Mol. Phys., 17, No. 2, 197?204 (1969).
5. Yu. V. Rakitskii, S. M. Ustinov, and I. G. Chernorutskii, Numerical Methods of Solving Rigid Problems [in Russian], Nauka, Moscow (1979).