Subject to investing

[Sam Borkton]

Hello BiggerPockets community! I am a real estate investing newbie looking to get started and was recently introduced to the model of buying properties "subject to." I am having a relatively difficult time finding articles about this model on the BiggerPockets website but have seen other videos on YouTube from Connected Investors and Flipster. I have watched many webinars from BiggerPockets, but I have never heard anyone talk about "subject tos" before.

Are there any good books on this model so that I can educate myself more to get started? 

What are some general pitfalls and concerns?

Any help is appreciated!