– Arturus Observatory Blog (Xavier Debeerst): http://debeerst.ning.com/polarex-unitron-telescopes
– Cave-Astrola Web-site: http://www.cave-astrola.com/
– Industrial Property Digital Library: http://www.ipdl.inpit.go.jp/homepg_e.ipdl
– Kasai Trading Company: http://www.kasai-trading.jp/englishindex.htm
– Mizar Observatory: http://home.solcon.nl/e.fledderus/historisch/Historisch-site/index.html
– Office for Harmonization of the Internal Market (Trademarks and Design): https://oami.europa.eu/ohimportal/en/home
– United States Patent and Trademark Office: http://www.uspto.gov/products/online-services.jsp
– Yahoo Unitron and Polarex Groups: https://groups.yahoo.com/neo/groups/UnitronTelescopes/info