evidence: American sweetgum tree ball (spiny seed pod) [...] Shikimic acid [edit]L. styraciflua seeds may be a renewable source of shikimic acid.[32] [...] - ^ "Sweetgum", McGraw-Hill Concise Encyclopedia of Science and Technology, New York: McGraw-Hill - ^ Kormanik, Paul P. "Liquidambar styraciflua L. – Sweetgum" Archived 11 July 2015 at the Wayback Machine from Silvics of North America: Volume 2:Hardwoods. Agriculture Handbook 654. U.S. Department of Agriculture, Forest Service, Washington, D.C. 1965 - ^ Philip Graitcer (17 July 2011). "Chopsticks Carry 'Made in America' Label". Voanews.com. Retrieved 21 December 2012.