Merriam-Webster Unabridged(MWU). (Online subscription-based reference service of ميريام وبستر, based on Webster's Third New International Dictionary, Unabridged. Merriam-Webster, 2002.) Headword tractor. Accessed 2007-09-22. نسخة محفوظة 2018-09-27 في Wayback Machine
Merriam-Webster Unabridged(MWU). (Online subscription-based reference service of ميريام وبستر, based on Webster's Third New International Dictionary, Unabridged. Merriam-Webster, 2002.) Headword tractor. Accessed 2007-09-22. نسخة محفوظة 2018-09-27 في Wayback Machine