References
- Pohl (1912) Die Physik der Eontgenstrahlen, Braunschweig.p. 104.
- Thoraeus (1936) Acta Radiol., p. 161.
- Behnken and Nitka (1935) Physikal. Zeitschrift, 36, p. 459.
- Wooten (1919) Phys. Rev., 13, p. 71.
- Thoraeus Acta Radiol.
- Widmann (1935) Amer. Journ. of Roentgenol. and Rad. Ther., Nov, p. 644.