Robert O. Wilson, MD (October 5, 1904 – November 16, 1967) was an American physician born to Protestant missionaries Wilbur F. Wilson and Mary Rowley Wilson in Nanjing, China.
 Wilson attended Princeton University and subsequently obtained his medical training at Harvard Medical School, graduating in 1929.
 He returned to Nanjing in 1936, where he assumed a housestaff position at Drum Tower Hospital of Gin Ling University (Nanjing University).
 Amidst the chaos and bloodshed that followed in the years leading up to the Japanese occupation of Nanjing, Wilson worked tirelessly at his post, eventually becoming one among only a handful of physicians who had not left the city by 1937.
Dartmouth College ( ) is a private Ivy League research university in Hanover, New Hampshire, United States.
 Established in 1769 by Eleazar Wheelock, it is the ninth-oldest institution of higher education in the United States and one of the nine colonial colleges chartered before the American Revolution.
 Although founded as a school to educate Native Americans in Christian theology and the English way of life, Dartmouth primarily trained Congregationalist ministers throughout its early history before it gradually secularized, emerging at the turn of the 20th century from relative obscurity into national prominence.
The Brown University School of Engineering is the engineering school at Brown University, a private Ivy League research university located in Providence, Rhode Island.
 The school offers both graduate and undergraduate study in the field.
 Undergraduate students may declare their major in engineering as late as the end of their sophomore year.
The Amos Tuck School of Business Administration is the graduate business school of Dartmouth College, an Ivy League research university in Hanover, New Hampshire, United States.
 Founded in 1900, Tuck is the oldest graduate school of business in the world, and was the first institution to offer master's degrees in business administration.
 It is one of six Ivy League business schools.
Princeton University is a private Ivy League research university in Princeton, New Jersey, United States.
 Founded in 1746 in Elizabeth as the College of New Jersey, Princeton is the fourth-oldest institution of higher education in the United States and one of the nine colonial colleges chartered before the American Revolution.
 The institution moved to Newark in 1747, then to the current site nine years later, where it was renamed Princeton University in 1896.
Harvard University is a private Ivy League research university in Cambridge, Massachusetts, established in 1636, whose history, influence, and wealth have made it one of the world's most prestigious universities.
Yale University is an American private Ivy League research university in New Haven, Connecticut.
 Founded in 1701, it is the third-oldest institution of higher education in the United States and one of the nine Colonial Colleges chartered before the American Revolution.
Columbia University (Columbia; officially Columbia University in the City of New York), established in 1754, is a private Ivy League research university in Upper Manhattan, New York City, often cited as one of the world's most prestigious universities.
The University of Pennsylvania (commonly known as Penn or UPenn) is a private Ivy League research university located in Philadelphia, Pennsylvania, United States.
 Incorporated as The Trustees of the University of Pennsylvania, Penn is one of 14 founding members of the Association of American Universities and one of the nine colonial colleges chartered before the American Revolution.
Brown University is a private Ivy League research university in Providence, Rhode Island, United States.
 Founded in 1764 as the College in the English Colony of Rhode Island and Providence Plantations, Brown is the seventh-oldest institution of higher education in the United States and one of the nine colonial colleges chartered before the American Revolution.

Question: Which private Ivy League research university did Robert O Wilson attend?
Answer: Princeton University