I found the lecture notes that made this claim on internet archive https://web.archive.org/web/20031127062932/http://www.augustana.ca/~mohrj/courses/1999.fall/c

I found the lecture notes that made this claim on internet archive https://web.archive.org/web/20031127062932/http://www.augustana.ca/~mohrj/courses/1999.fall/csc210/lecture_notes/hashing.html https://web.archive.org/web/20031127062932/http://www.august... It doesn't give any sources unfortunately.