Cabinets of Experimental Philosophy in Eighteenth-Century Europe, BRILL, Jun 21, 2013, pg. 22, Accessed vial Google Books, https://books.google.com/books?id=DJKiWjpCgAkC&pg=PA22 (accessed 07/30/2015)
"Pieter Hendrik van Cittert," WikiMan, http://men.wikia.com/wiki/Pieter_Hendrik_van_Cittert (accessed 07/30/2015)