http://books.google.com/books?vid=ISBN9781852331931
1436
http://books.google.com/books?vid=ISBN1852331933
2
http://books.google.com/books?vid=ISBN9780521874076
2
http://telescope.com/observing-the-moon/p/99805.uts
1
http://books.google.com/books?vid=ISBN9781139464949
1