1. J. W. Mellor: In: A Comprehensive Treatise of Inorganic and Theoretical Chemistry 10 (1948) 833.
2. The Actinide Elements. Edited by G. T. Seaborg and J. J. Katz: New York, 1954.
3. G. S. Deshmukh and L. K. Swamy: Analyt. Chem. 12 (1951) 218.
4. V. P. Nesterenko: Synthesis of the Selenite of Thorium. Copyright Certificate N 582647 (1977).
5. P. Paulik, I. Paulik and L. Erdey: J. Analyt. Chem. 160 (1964) 241.