International Union for the Protection of New Varieties of Plants. Convention for the Protection of Plants : message from the President of the United States transmitting the International Convention for the Protection of New Varieties of Plants of December 2, 1961, as revised at Geneva on November 10, 1972, on October 23, 1978, and on March 19, 1991, and signed by the United States on October 25, 1991. Washington D.C.. UNT Digital Library. http://digital.library.unt.edu/ark:/67531/metadc31096/. Accessed May 28, 2016.