1. S-R. Sänger,Physik. Zeit., 1926,27, 556;Helv. Physic. Acta, 1930,3, 161.
2. Si-S. C. Sircar,Ind. Jour. Phys., 1928,3, 181.
3. S & St-R. Sänger and O. Steiger,Helv. Physic. Acta, 1929,2, 411;Ibid. Helv. Physic. Acta, 1929,2, 136.
4. F-O. Fuchs,Zeit. fur. Physik., 1930,63, 824.
5. M & S G-P. C. Mahanti and D. N. Sengupta,Jour. Ind. Chem. Soc., 1928,5, 673;Ind. Jour. Phys., 1928,3, 181.