Wikipedia: Free Verse (verse libre)
Brief article exploring the style of poetry that is based on cadences more irregular than those of traditional poetic meter.
en.wikipedia.org/wiki/Free_verse
UVic Writer's Guide: Free Verse
Definition and Whitmanesque example of the irregular meter.
web.uvic.ca/wguide/Pages/LTFreeVerse.html
After Free Verse: The New Non-Linear Poetries
By Marjorie Perloff. Examines the history, implications, and different kinds of free verse.
wings.buffalo.edu/epc/authors/perloff/free.html
Many Births of Free Verse, The
By Daniel Ust. Review of Henry Tompkins Kirby-Smith's book The Origins of Free Verse.
uweb.superlink.net/neptune/FreeVers.html