The bit-babbler package is: Copyright (C) 2003 - 2018, Ron Lee It is distributed according to the terms of the GNU GPL v2. On Debian systems, the complete text of the GNU GPL can be found in /usr/share/common-licenses/GPL-2 The implementation of poz() and pochisq() in include/bit-babbler/chisq.h are (heavily) based on public domain code from John "Random" Walker's ENT test suite, which in turn took it with minimal modification from public domain code by Gary Perlman of the Wang Institute. The original code for ENT can be found at The changes to poz() and pochisq() made in this package are released into the public domain as well.