Answer to Question #61306 in Genetics for Sanjukta Ghosh

Question

Is there a good book that explains operons: lac operon and trp operon in details.

I was reading the functioning of the trp repressor protein from 'Principles of genetics-by Snustard and Simmons',they have mentioned that the binding of the repressor-corepressor complex to Operator prevents the transcription of the structural genes. But they don't explain how.

Khan academy says that the repressor-corepressor complex physically comes in the way of the RNA polymerase. They have used this diagram below which shows that the large RNA polymerase cannot bind to the promoter site due to steric hindrance.
For the diagram: http://biology.stackexchange.com/questions/50757/problem-in-understanding-operon

I'm looking for a more authentic source to study exactly how this RNA polymerase is being prevented from transcribing the DNA in both the operons.