I've heard that it is possible to get pregnant after having a tubal ligation. Is it possible to get pregnant after having a tubal 16 years ago without any intervention of IVF or reversals? Are there any medical research publications on this subject?

Without doing any research for you I can tell you that I have a brother. He was born 10 years after my mother's tubal.

You can look up this info on Medscape.com, I am sure there are articles there, or even EntrezPubmed (if you can understand the medical jargon).