In essence, a famous health magazine developed the regime, and it is partly inspired by the Tabata interval training.
I have come up with a lower ab and general workout that will define your abdominals, most of all the inguinal ligaments and the obliques.
What is great about it is that you can do it without equipment other than one's cloth. I used the elastic/resistance bands in my feet, but you can avoid them, especially if you are just starting.
The video will be ready later, for now enjoy the diagram, which I recommend you print: