Please see external links for images of buttons (front & back) made from the material(s) in question. ("NBS name" refers to labelling used by the National Button Society, USA.)
^ abcdefghijklButton Country (2010). "Other Materials (Section 15)". Georgia, USA: buttoncountry.com. Archived from the original on 5 June 2010. Retrieved 6 March 2010. (To view reverse of button, hover mouse over image.)
^Luscomb, Sally C. (2003). The Collector's Encyclopedia of Buttons, p.100. Atglen, PA: Schiffer. p. 242. ISBN0-7643-1815-2. LCCN2003101645.
^ abButton Country (2010). "Synthetic Polymers (Section 12)". Georgia, USA: buttoncountry.com. Archived from the original on 4 June 2010. Retrieved 6 March 2010. (To view reverse of button, hover mouse over image.)
^Morrell, George (2010). "1935 - Making Casein Buttons". Sampling One Hundred Years of Button Patents. Georgia, USA: Peach State Button Club. Archived from the original on 12 October 2010. Retrieved 12 March 2010.
Bibliography
Luscomb, Sally C. (2003). The Collector's Encyclopedia of Buttons. Atglen, PA: Schiffer. p. 242. ISBN0-7643-1815-2. LCCN2003101645.
Osborne, Peggy A. (1997). Button, button : identification and price guide. Atglen, PA: Schiffer. p. 167. ISBN0-7643-0082-2. LCCN92063104.
Peacock, Primrose (1978). Discovering old buttons. Discovering series ; no. 213. Rosemary Godsell (illus.). Aylesbury, UK: Shire Publications. pp. 76. ISBN0-85263-445-5.