His thesis, titled "Boundary Layer Problem for a Liner Parabolic Differential Equation," was written under the guidance of the renowned Norman Levinson.
[4] While still a graduate student in 1954, he secured a summer position as a Scientific Officer at the National Research Development Council (NRDC) in London, England.
In 1956, he made a move to the University of Minnesota, joining the Department of Mathematics at the then Institute of Technology(now College of Science and Engineering).
[4] Remarkably, Don collaborated with more than 40 co-authors, aligning with his perspective that mathematics research is akin to a "team sport".
[4] In June 2001, a conference titled "Nonlinear Phenomena in Science" took place at the Free University of Amsterdam, dedicated to honoring Don on his 70th birthday.