"OB Associations"(PDF) (بالإنجليزية). GAIA: Composition, Formation and Evolution of the Galaxy. 6 Apr 2000. Archived from the original(PDF) on 2016-03-03.
"OB Associations"(PDF) (بالإنجليزية). GAIA: Composition, Formation and Evolution of the Galaxy. 6 Apr 2000. Archived from the original(PDF) on 2016-03-03.