In 1983, Zapf completed the typeface "AMS Euler" with Donald Knuth and graduate students in Knuth's and Charles Bigelow's digital typography program at Stanford University, including students Dan Mills, Carol Twombly, and David Siegel and Knuth's computer science PhD students Scott Kim and John Hobby, for the American Mathematical Society. Euler digital font production was eventually finished by Siegel as his M.S. thesis project in 1985. Euler is a typeface family for mathematical composition including Latin, Fraktur and Greek letters. After Siegel finished his studies at Stanford and was interested in entering the field of typography, he told Zapf his idea of making a typeface with a large number of glyph variations and wanted to start with an example of Zapf's calligraphy, which had been reproduced in a publication of the Society of Typographic Arts in Chicago.