How old was Jesus?

I am wondering about the traditional belief that Jesus was crucified at the age of about 33.

If Jesus was crucified when he was about 63 years old this would place his birth somewhere in the middle of the well documented story of Mariamne Herod and Joseph Herod described in the on-line Jewish Encyclopedia for the entry under Mariamne.

Here is the link to the Jewish Encyclopedia entry:

I am now trying to find the sources and especially confirmation of the sources that say Jesus was about 33 when he was crucified.

This search seems most interesting and any help would be appreciated.