1. Dill DB, Yousef MK, Nelson JD. 7 Appl Phys 1973; 35:231-5.
2. _7 Pharnz Exp 7her;Kollins, J.; Bullard, R.W.,1964
3. Craig FN, Cummings EG, Froehlich HL, Robinson PF. J Appl Phys 1969;27:498-502.
4. Craig FN. J Appl Phys 1970;28:779-83.
5. Scandj7 Cl/n Lab Invest;Mogensen, C.E.,1976