Evolution of Romance lgs

Hello,
What is a good book/website on the evolution/difference among romance
lgs. I am more focused on phonology and grammar evolution rather than
vocabulary or people movements. A source that will enable me to predict
the outcome of say an inherited latin verb like v'endere, that if
it's retained, will be vend'er in Spanish, v'endre in French, v'endre
in Catalan etc.

thanks in advance

Harald