Das, K.; Chaudhuri, B. K. Study of phase transition in iron(II) fluoroborate hexahydrate and iron(II) fluoroborate hexahydrate-D2 at 274 K. Indian Journal
Ostrovskaya, T. V.; Amirova, S. A.; Startseva, N. V. Chemical transformations of iron, cobalt, and nickel tetrafluoroborates. Zhurnal Neorganicheskoi Khimii, 1967