Brown Univ., Providence, RI (USA); Massachusetts Inst. of Tech., Cambridge (USA)(Brown Univ., Providence, RI (USA); Massachusetts Inst. of Tech., Cambridge (USA))1987.
Brown Univ., Providence, RI (USA). Dept. of Physics; Pennsylvania Univ., Philadelphia (USA). Dept. of Physics(Brown Univ., Providence, RI (USA). Dept. of Physics; Pennsylvania Univ., Philadelphia (USA). Dept. of Physics)1985.