David, D.(2004).The universal book of astronomy: from the andromeda galaksi to the zone of avoidance .Norwood, New Jersey:John Wiley n Sons.
Gaya MLA
Darling, David."The universal book of astronomy: from the andromeda galaksi to the zone of avoidance".Norwood, New Jersey:John Wiley n Sons,2004.Textbook.