The Royal Road to Card Magic (1983) by Fred Braue & Jean Hugard Page 183 et seq.
Personal Comment: We all love the slop shuffle don't we. And this routine is so darn practical and deceptive. I have done it many times (slightly differently) and I know that it hits hard. I cannot praise this enough. There are many weird version of righting the cards, but this is so good, that it cannot be dismissed.