http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.385.1265&rep=rep1&type=pdf http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.385.1265&rep=rep1&type=pdf
https://www.youtube.com/watch?v=Mi_GaJTsy8Q https://www.youtube.com/watch?v=Mi_GaJTsy8Q