Thomson South-Western. (2007). Virtual tutor system: Michigan version 3.0. Thomson South-Western.
Παραπομπή Chicago StyleThomson South-Western. Virtual Tutor System: Michigan Version 3.0. Thomson South-Western, 2007.
Παραπομπή MLAThomson South-Western. Virtual Tutor System: Michigan Version 3.0. Thomson South-Western, 2007.
Πρόσοχή: Οι παραπομπές μπορεί να μην είναι 100% ακριβείς.