The Retroflex sounds

The retroflex sound is a consonant sound produced with the tip of the tongue curled back toward the hard palate. 
RETRO: BACK
FLEX: FOLD
This is a video about the retroflex sounds:

https://www.youtube.com/results?search_query=retroflex+sounds





This is a link about the retroflex consonats, in here you will find the information about it:

http://facweb.furman.edu/~wrogers/phonemes/phono/retro.htm

This is an important tool in which you can practice the exercises about the retroflex sounds:

https://books.google.com.gt/books?id=gsTiWZoUU9oC&pg=PA158&lpg=PA158&dq=exercises+of+the+retroflex+sounds&source=bl&ots=oUtPqAT9rY&sig=8Go28LFvU7uMO7sH_7RRhrzfj9Q&hl=es-419&sa=X&ei=X8kAVZ6cKsa1sQS924GYBQ&ved=0CC4Q6AEwAg#v=onepage&q=exercises%20of%20the%20retroflex%20sounds&f=false