Analysis of information sources in references of the Wikipedia article "Thomas Royen" in English language version.
I know of people who worked on it for 40 years," Donald Richards, a statistician from Pennsylvania State University, told Natalie Wolchover at Quanta Magazine. "I myself worked on it for 30 years.
"Ich kenne Leute, die daran 40 Jahre gearbeitet haben", sagte er dem "Quanta Magazine".