The Structure Features of Synthetic Apatites with REE Impurities by Data of Spectroscopy and X-Ray Analysis Methods: I. Hydroxylapatites - E. A. Kalinichenko; A. B. Brik; A. M. Nikolaev; A. M. Kalinichenko; O. V. Frank-Kamenetskaja; A. V. Dubok; N. N. Bagmut; M. A. Kuzmina; I. E. Kolesnikov (Mineralogical journal, 2015)