Емисиона маглина — разлика између измена

* {{Cite book|author = Patrick Moore | year = 2000 | title = The Data Book of Astronomy | publisher = IOP Publishing Ltd |location = Бристол | language = {{ен}} | pages = 308 стр | id = ISBN 0-7503-0620-3| ref = harv}}

* {{Cite book|author = Ian Ridpath | year = 2006 | title = Astronomy (Eyewitness Companions) | publisher = DK Publishing, Inc. |location = Њујорк | language = {{ен}} | pages = 63. стр | id = ISBN 0-7566-1733-2| ref = harv}}