(1962). National recreation survey. Washington, D.C: Outdoor Recreation for America.
Παραπομπή Chicago StyleNational Recreation Survey. Washington, D.C: Outdoor Recreation for America, 1962.
Παραπομπή MLANational Recreation Survey. Washington, D.C: Outdoor Recreation for America, 1962.
Πρόσοχή: Οι παραπομπές μπορεί να μην είναι 100% ακριβείς.