"kwel-1". Kwel-1. The American Heritage® Dictionary of the English Language: Fourth Edition. 2000. The American Heritage Dictionary of the English Language (4th ed.). 2000. Archived from the original on 2005-12-30.
etymonline.com
Harper, Douglas (2001). "Sabre". Online Etymology Dictionary.
"kwel-1". Kwel-1. The American Heritage® Dictionary of the English Language: Fourth Edition. 2000. The American Heritage Dictionary of the English Language (4th ed.). 2000. Archived from the original on 2005-12-30.