Wikimedia
Wikipedia: Caesura
Encyclopedia article that defines and gives many examples of Caesura in poetry. Examples are taken from Latin, Old English, and Middle English poetry. Also defines different forms of Caesura (such as masculine caesura and feminine caesura).
Other
So You wanna.com: So You Wanna Learn About Poetic Form?
Discusses poetic form and the basic unit of form, the stanza. Also defines many related terms including couplet, triplet (tercets), quatrain, sesten (sestina), rhyme royal, ottava rima, Spenserian stanza, sonnet, and villanelle.
University of Victoria (Canada)
The U Vic Writer's Guide: Literary Term: Stanza
Contains a short explanation of the poetic stanza. Also defines Verse paragraphs. Unfortunately, no examples are given, but there are a few links to related terms.
Rutgers University
Rutgers University: Glossary of Literary and Rhetorical Terms
This is a glossary of literary and rhetorical terms in alphabetical order by Jack Lynch, Rutgers University. Click the desired link to find the definition.