Ushchapivska, T. I.; Zatovsky, I. V.; Slobodyanik, M. S.; Kuzmin, R. M. Conductive Properties of Solid Solutions Na3????2xFe2????XNbx(PO4)3 (x =  1:5). Dopov. Nac. akad. nauk Ukr. 2024, 95-100.