Semi-insulating GaAs: A possible substrate for a field-assisted positron moderator - Shan, Y. Y.; Au, H. L.; Ling, C. C.; Lee, T. C.; Panda, B. K.; Fung, S.; Beling, C. D.; Wang, Y. Y.; Weng, H. M. (Springer, 1994)
http://dx.doi.org/10.1007/BF00348229
Keywords: ZL; U