1. Devlin, S. S., Jost, J. M., Shiozawa, L. R.: Wadd Technical Report 60-11, 1960.
2. Dolega, U.: Z. Naturforsch. 15a (1963) 809.
3. Kulshrestha, K.K., Pandya, A., Mathur, C.: Mater. Chem. Phys. 17 (1987) 357.
4. Shahane, C.S., Sutrave, D.S., Deshmukh, L.P.: Indian J. Pure Appl. Phys. 34 (1996) 153.
5. Mohanchandra, K.P., Uchil, J.: Thin Solid Films 305 (1997) 124.