Pogge, Richard W. Stellar distances. Astronomy 162: Introduction to Stars, Galaxies and the Universe. Ohio State University. October 31, 2006 [March 20, 2009]. (原始内容存档于1999-09-01).
Pogge, Richard W. Stellar distances. Astronomy 162: Introduction to Stars, Galaxies and the Universe. Ohio State University. October 31, 2006 [March 20, 2009]. (原始内容存档于1999-09-01).