New York Giants Team History and Timeline - Sports Illustrated
New York Giants Preservation Society (BASEBALL) - THE FAMED PG'S Happy New Year! This is a thorough history of the Polo Grounds from a 2016 blog by Liam McArthur. Thanks to NYGPS
Columbia Football Stadiums Through the Years - Columbia University Athletics
Polo Grounds - history, photos and more of the New York Giants former ballpark
NFL in NYC: pro football's history in the five boroughs - Curbed NY
June 28, 1911: Mathewson shuts out Boston in Giants' first game at new Polo Grounds – Society for American Baseball Research
Polo Grounds, Manhattan, NY, October 2, 1951 – Game Two of the memorable playoff series between the NY Giants and Brooklyn Dodgers
Polo Grounds - history, photos and more of the New York Giants former ballpark