Because C was developed at Bell Labs in the pre-internet 70s, the first "official" documentation was the book by K&R. Due to the language's popularity, it was standardized first by ANSI, then by ISO. So these days, the closest thing to a "source of truth" for the language is the standard published by ISO. That working group's website is here: http://www.open-std.org/jtc1/sc22/wg14/
Of course, standards documents are not really entry points, as they are extremely dry, technical documents. Which is why I think the answer to your question is "no".
I think your best bet would be to start with the second edition of "The C Programming Language" by Kernighan and Ritchie, then work your way "into the future" by looking at books on C published in the last decade.
HTH