These are Harmonic Patterns. Basically they are based upon channel breakouts and Fibonacci levels. They are very effective patterns for finding the reversals. Basically they provide good opportunity to buy low and sell higher.
You can find good material by Mr. Scott Carney. He is a well known author. Mr. Jason Stapleton and Mr. Akil Stokes are well known Harmonic traders and tutors too.
Plenty of material is also available online to get the basics.