I've always thought that the two-form resonance structure of ozone was the scientific concensus (from Wikipedia]:
Then today I found two other opinions. A three-form structure:
And a four-form structure:
Is there a consenus? Are the two and three-form representations just simplifications of the four-form structure? Please include references.
EDIT: The second resonance structure on the four-form image above is drawn incorrectly, as pointed out by @ron. The upper oxygen atom should have a lone pair and a positive charge, just like the second structure of the two-form.