The Vowel roundedness reference article from the English Wikipedia on 24-Jul-2004
(provided by Fixed Reference: snapshots of Wikipedia from wikipedia.org)

Vowel roundedness

Sponsorship the way you would do it
In phonetics, vowel roundedness refers to the amount of rounding in the lips during the articulation of a vowel. Vowels are usually described as a rounded vowel or unrounded vowel, although some vowels are described without reference to their roundedness, such as the mid central vowel and the near-open central vowel.

See also