A. R. Noviyanti, B. Prijamboedi, I. N. Marsih, and I. Ismu, “Hydrothermal Preparation of Apatite-Type Phases La9.33Si6O26 and La9M1Si6O26.5 (M = Ca, Sr, Ba)”, J. Math. Fund. Sci., vol. 44, no. 2, pp. 193-203, Jul. 2013.