These are my answers for selected exercises for the book Structure and Interpretation of Computer Programming, by Harold Abelson and Gerald Jay Sussman with Julie Sussman.
The book itself is © 1996 by The Massachusetts Institute of Technology and is licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported License.
Answers that include or are derived from example code from the text are clearly marked with a CC-by-sa license statement. Other answers, code, or text in this project that is not derived from or does not include example code is hereby dedicated to the public domain using the CC0 1.0 Public Domain Dedication.