Robert Williams
发表
Jan Peters,
George Sonneborn,
Robert P. Kirshner,
1993
.
Massimo Stiavelli,
Norbert Zacharias,
Stefano Casertano,
2000
.
M. F. Bode,
Matthew A. Greenhouse,
D. K. Lynch,
2004
.
Comparative Absorption and Emission Abundance Analyses of Nebulae: Ion Emission Densities for IC 418
Edward B. Jenkins,
Michigan State University,
Jack A. Baldwin,
2002,
astro-ph/0210551.
Henry C. Ferguson,
Mark Dickinson,
Robert Williams,
2000
.