Monique Ankoné, Erik Arends "Exercise 1" in The invisible Universe, EU Universe Awareness, p. 57 ISBN: 978-94-91760-07-5. No name, no license, "Credit: Wikimedia Commons" on page 66, "This EU-UNAWE book is licensed under a Creative Commons Attribution-Non-Commercial-Share Alike 3.0 Unported License.", link to Commons upload directory in corresponding [www.unawe.org/static/archives/education/other/Radioastronomy_activity_booklet.rtf rtf file]
.jpg&oldid=145500092){kind=link}