AILSA ALLABY and MICHAEL ALLABY. "hog's back." A Dictionary of Earth Sciences. 1999. Encyclopedia.com. 10 Nov. 2009 <http://www.encyclopedia.com>.
AILSA ALLABY and MICHAEL ALLABY. "hog's back." A Dictionary of Earth Sciences. 1999. Encyclopedia.com. (November 10, 2009). http://www.encyclopedia.com/doc/1O13-hogsback.html
AILSA ALLABY and MICHAEL ALLABY. "hog's back." A Dictionary of Earth Sciences. 1999. Retrieved November 10, 2009 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O13-hogsback.html