^Kalieva, K.; Stretkova, Z. V.; Babynina, N. A.; Gordienko, L. N.; Votoyarov, M.; Yakimov; Sakavov, I. E.; Mustaev, A. K. X-ray diffraction studies of praseodymium, neodymium, europium, terbium, dysprosium, erbium, holmium, and terbium orthophosphates. Tr. Kirg. Univ., Ser. Khim. Nauk, 1972. 2: 84-89.