Παραπομπή APA

(1969). Growth centers and their potentials in the Upper Great Lakes region. Washington, D.C: [s.n.].

Παραπομπή Chicago Style

Growth Centers and Their Potentials in the Upper Great Lakes Region. Washington, D.C: [s.n.], 1969.

Παραπομπή MLA

Growth Centers and Their Potentials in the Upper Great Lakes Region. Washington, D.C: [s.n.], 1969.

Πρόσοχή: Οι παραπομπές μπορεί να μην είναι 100% ακριβείς.