Sources on the Open Ruy Lopez


Recently,when defending against e4, i have switched from my beloved Alekhine defence to the more common ...e5. My idea is to play the Open variation of the Ruy Lopez (1.e4 e5 2.Nf3 Nc6 3.Bb5 a6 4.Ba4 Nf6 5.0-0 Nxe4). I quite like the positions I've got so far, but i think it's time to study the line more seriously.
I wonder if someone can suggest me a good source, not necessarily including very deep lines but just explaining the basic concepts. An alternative might be to study some master games (for example GM Vocaturo, the recent winner of Tata Steel C, uses the open quite often). 
What's your suggestion?
Thanks in advance.

Thanks for the answer. So you never used a theoretical source?

BTW, what is your answer against 6.Re1? This should be unambitious but it's seen very often in blitz. If i remember correctly the 2 accepted reactions are 6...Nc5 and 6...b5, right?


thanks to everyone for the answers! Sorry for the lack of feedback but i was without an internet access during the weekend.

Regarding the 6.Re1 variation i have come across some nicely annotated games showing 6...Nc5 as the best variation, as both offtherook and paulgottlieb said.

I will give a look to the suggested book!

Thanks to everyone!