Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Hans R. Guggisberg, Zusammenhänge in historischer Vielfalt. Humanismus, Spanien, Nordamerika. Eine Aufsatzsammlung, hg. unter Mitarbeit von Christian Windler, Basel 1994 (Basler Beiträge zur Geschichtswissenschaft 164)
Spatial diffusion: Gould, Peter R.(1969): Research Paper No. 4, Commission on College Geography, Association of American Geographers. Washington, DC 72s.