The answer to the three houses problem I posed below (earlier in the week).
The Skeptic's Field Guide by Theo Clark and Jef Clark is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License.
The Skeptic's Field Guide by Theo Clark and Jef Clark is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License.