1998, Walt Wolfram, Natalie Schilling-Estes, American English: Dialects and Variation[1]
... for “Park the car in Harvard Yard.” Interestingly, one of the most stereotypically r—less ... pahk the cah 'park the car' as you shape your answer.
2000, Allan A. Metcalf, How We Talk: American Regional English Today[2]
The "New England broad a"Park the car in Harvard Yard. That saying is a well-known test for New England pronunciation. If you say "Pahk the car in Hahvahd Yahd," ...
2003, Kim Grant, Boston: With Cape Cod & New England Getaways.[3]
The Boston dialect is famous for broad-vowel English; Pahk the cah in Hahvahd Yahd (translation: Park the car in Harvard Yard) is the common illustration of the peculiar 'r.'