How are columbiformes (doves and pigeons) related to psittaciformes?

["Dora Smith" <villandra@austin.rr.com>]

I have come across several tables of bird phylogeny that state that
psittaciformes (parrots) and columbiformes (doves and pigeons) are closely
related - and placed in various diverse locations in the phylogenetic
scheme.

Explanations of this idea are so vague they do not even tell me if the
evidence is genetic or morphological.

As nearly as I can figure out with my very incomplete at the moment access
to journal articles, Charles Sibley and company found parrots to be most
closely related to - woodpeckers?

What can anyone tell me about what reason there is to believe psittaciformes
and columbiformes are closely related, and can anyone suggest some good
sources on that subject.

Thanks+ACE-

Yours,
Dora Smith
Austin, Texas
villandra+AEA-austin.rr.com