This article is from the Puzzles FAQ, by Chris Cole firstname.lastname@example.org and Matthew Daly email@example.com with numerous contributions by others.
What is the solution to Soma Cubes?
The soma cube is dissected in excruciating detail in volume 2 of
"Winning Ways" by Conway, Berlekamp and Guy, in the same chapter as the
excruciatingly detailed dissection of Rubik's Cube.