Telescopul spaţial Hubble împlineşte 27 de ani de funcţionare | Jurnal.md
Telescop - Wikipedia
ALMA telescope dishes | ESO
The Gregorian telescope employs a concave secondary mirror that reflects the image back through a hole in the primary mirror. | Webel IT Australia
English: Chabot Space & Science Center's 1883, 8-inch, Alvan Clark refracting telescope, Leah; 23 December 2006 (original upload date); Transferred from en.wikipedia to Commons by Jacopo Werther.; Myowncompass at English Wikipedia Stock