Program construction for macromolecule atomic model refinement based on the fast Fourier transform and fast differentiation algorithms; erratum

In Lunin & Urzhumtsev [Acta Cryst. (1985), A41, 327-333] references to Lifshitz (Agarwal, 1981) on pages 327 and 329 should be amended to Lifchitz (Agarwal, 1981).