In addition to the IEEE standards, numerous other resources are available on program documentation.
Spinellis, Diomidis. Code Reading: The Open Source Perspective. Boston, MA: Addison-Wesley, 2003. This book is a pragmatic exploration of techniques for reading code, including where to find code to read, tips for reading large code bases, tools that support code reading, and many other useful suggestions.
SourceForge.net. For decades, a perennial problem in teaching software development has been finding life-size examples of production code to share with students. Many people learn quickest from studying real-life examples, but most life-size code bases are treated as proprietary information by the companies ...