"Earth Society Foundation" . "Earth Society Foundation". http://www.earthsocietyfoundation.org . Retrieved 2010-04-22. ^ http://quod.lib.umich.edu/cgi/f/findaid/findaid-idx?c=bhlead;cc=bhlead;view=text;rgn=main;didno=umich-bhl-07183 ^ http://www.sph.umich.edu/about/timeline.html ^ http://ns.umich.edu/htdocs/releases/story.php?id=2535 ^ "A Memento Mori to the Earth" . Time . 1970-05-04. http://www.time.com/time/magazine/article/0,9171,943782,00.html . ^ Finney, John W. (April 15, 1971). "Muski says FBI spied at rallies on '70 Earth Day" . The New York