Robert L. Pigford
发表
Robert L. Pigford,
1963
.
Thomas K. Sherwood,
Robert L. Pigford,
T. Sherwood,
1952
.
Hans Frauenfelder,
Gene I. Rochlin,
Warren E. Falconer,
1978
.
W. R. Marshall,
Robert L. Pigford,
W. Marshall,
1947
.