1. Bykadorov I. A. On quasiconvexity conditions of sums of linear fractional functions (Russian). Optimizatsiya. - Novosibirsk, 1986. Vyp. 39 (56). p. 2541.
2. Bykadorov I. A. Differential quasiconvexity criteria for finite sums of linear fractional functions (Russian). Novosibirsk, 1989. 23 p. (Preprint/AN SSSR, Sib.otdelenie. Inst. mathematiki, No. 24 ).
3. Bykadorov I. A. Differential quasiconvexity criteria for ratios of the polynomials of several variables (Russian). Novosibirsk, 1990. 20 p. (Preprint/AN SSSR, Sib.otdelenie. Inst. mathematiki, No. 12 ).
4. Bykadorov I. A. Quasiconvexity conditions for some classes of fractional functions (Russian). Novosibirsk, 1990. 40 p. (Preprint/AN SSSR, Sib. otdelenie. Inst. matematiki, No. 18 )
5. Charnes A., Cooper W. W. Programming with linear fractional functionals. Nay. res. logist. quart. 1962. Vol. 9, No. 3–4. p. 181–186.