Barth F. W., 1932, Amer. Jour. Sci., 23, 350, 10.2475/ajs.s5-23.136.350
F. W., 1932, Amer. Jour. Sci., 24, 97, 10.2475/ajs.s5-24.140.97
Niexjwenkamp W., 1935, Z. Kristallogr., 92, 82, 10.1524/zkri.1935.92.1.82
1945, Amer. Min., 30, 526
Wyckoff R. W. G., 1925, Amer. Jour. Sci., 9, 448, 10.2475/ajs.s5-9.54.448