Sepanski, R.J.; Stoss, F.W. (eds.); Boden, T.A.; Kanciruk, P. & Farrell, M.P. TRENDS '90: A compendium of data on global change, report, August 1, 1990; (https://digital.library.unt.edu/ark:/67531/metadc1207824/m1/1/: accessed March 19, 2019), University of North Texas Libraries, Digital Library, digital.library.unt.edu; .