People should check out P.J. Plauger's books, specifically;

1) The Standard C Library - One of the best books to learn about industrial-strength C programming implementation techniques.

2) The C++ Standard Template Library - Similar to above but for C++ STL.

Both the above were licensed through his company Dinkumware. I had an opportunity to license, study and use them for a project and found the experience quite rewarding. It is not as complicated and relatively easier to understand than GNU libc and libstdc++. Of course i have both the books which explain the implementation.

3) His other set of interesting books are the 3-vol Programming on Purpose; a series of essays on various topics. The 1st is on Software Design, the 2nd is on Software People and the 3rd is on Software Technology. They also contain lots of nuggets of wisdom which are still relevant today. My favourite is the one on software design - https://archive.org/details/programmingonpur0000plau