Python features are described and discussed in Python Enhancement Proposals ("PEPs") These describe the implementation, also PEPs often contain working Python Code to help explain the algorithm though the final implementation may be in C. If you need more details than can be gotten from the PEPs then you should take a look at the source code.
Note: PEPs are written from the perspective of what ever enhancement is being proposed rather than an overall description of the implementation. So for example there might a PEP for Dict-Comprehensions but not for Dicts as a whole. For a top down view of Python internals the source code is the place to go.