We discuss a method for monochromatic inverse scattering in three dimensions of [Novikov in Int. Math. Res. Papers 2005(6):287-349, 2005] and implemented numerically in [Alekseenko et al. in Acoust. J. 54(3), 2008]. This method is obtained as a development of the∂-approach to inverse scattering at fixed energy in dimension d ≥ 3 of [Beals and Coifman in Proc. Symp. Pure Math. 43:45-70, 1985] and [Henkin and Novikov in Usp. Mat. Nauk 42(3):93-152, 1987] and involves, in particular, some results of [Faddeev in Itogi Nauki Tech. Sovr. Prob. Math. 3:93-180, 1965, 1974] and some ideas of the soliton theory (in particular, some ideas going back to [Manakov in Usp. Mat. Nauk 31(5):245-246, 1976] and [Dubrovin et al. in Dokl. Akad. Nauk SSSR 229:15-18, 1976]). Also, our studies go back, in particular, to [Regge in Nuovo Cimento 14:951-976, 1959]. This article is an extended version of the talk given at International Conference in Mathematics in honor of G. Henkin at the occasion of his 65th birthday.