Não informado. University of Iowa studies in character. Institute of Character Research.
Παραπομπή σε μορφή Chicago (17η εκδ.)Não informado. University of Iowa Studies in Character. Iowa City, Iowa: Institute of Character Research.
Παραπομπή σε μορφή MLA (8th εκδ.)Não informado. University of Iowa Studies in Character. Institute of Character Research.
Πρόσοχή: Οι παραπομπές μπορεί να μην είναι 100% ακριβείς.