Robert E. Sheppard
发表
Peter W. Marshall,
Gayle S. Johnson,
Robert E. Sheppard,
1998
.
Gayle S. Johnson,
Robert E. Bachman,
Keith Porter,
2010
.
Gayle S. Johnson,
Robert E. Bachman,
Keith Porter,
2011
.
James C. Lin,
James K. Liming,
Robert E. Sheppard,
2001
.