The list is missing the Parks P-2 which had a radial engine. Richard Bach, the author of "Jonathan Livingston Seagull" had one and flew it into Parks field one day in 1968 to have Oliver Parks autograph the instrument panel.

The Parks P-1 was produced at Parks College of Aeronautical Technology which was founded by Oliver L Parks in 1927.
It was located in Cahokia, IL, about 10 miles southeast
of St. Louis, MO. The school taught aeronautical engineering, flying and A&P classes. Many MANY pilots were trained there in WW-II. In 1947, Oliver Parks donated the college to St. Louis University. The Illinois campus was closed in about 1997 with the college moving over to the St. Louis U main campus in mid-town St. Louis.