http://messier.seds.org/xtra/
history/m-m31_42.html (accessed 30 August
2016); see also http://messier.seds.org/m/m042.
html and http://messier.seds.org/
URL: https://www.flickr.com/people/24311648@N00 publication date: 7 April 2016 described at URL: https://www.flickr.com/photos/mastermaq/26282797115/ operator:
Wikimedia Community Conceived at a RasberryPi community event on 3 rd March 2016. Source I, the copyright holder of this work, hereby publish it under the
URL: https://www.flickr.com/people/24311648@N00 publication date: 7 April 2016 described at URL: https://www.flickr.com/photos/mastermaq/26282787235/ operator: