Open Game License v 1.0 Copyright 2000, Wizards of the Coast, Inc.
System Reference Document. Copyright 2000, Wizards of the Coast, Inc; Authors Jonathan Tweet, Monte Cook, Skip Williams, based on material by E. Gary Gygax and Dave Arneson.
Arcana Evolved. Copyright 2005, White Wolf Publishing; Author: Monte J. Cook and Sue Cook.
FATE (Fantastic Adventures in Tabletop Entertainment) © 2003 by Evil Hat Productions LLC; Authors Robert Donoghue and Fred Hicks.
Fudge System 1995 version © 1992-1995 by Steffan O’Sullivan, © 2005 by Grey Ghost Press, Inc.; Author Steffan O’Sullivan.
ICONS, Copyright 2010, Adamant Entertainment; Author Steve Kenson.
Items of Power and Ambition © 2012, Purple Duck Games. Author Sean Holland.
Pathfinder Roleplaying Game. Copyright 2008, 2009, Paizo Publishing, LLC; Author: Jason Bulmahn.
Spirit of the Century © 2006, Evil Hat Productions LLC. Authors Robert Donoghue, Fred Hicks, and Leonard Balsera.
The Complete Book of Eldritch Might. Copyright 2004, Malhavoc Press; Author: Monte J. Cook.
The Book of Experimental Might. Copyright 2008, Malhavoc Press; Author: Monte J. Cook.
The Sea of Stars RPG Design Journal, http://seaofstarsrpg.wordpress.com/ Copyright 2009-2010 Sea of Stars RPG; Authors: Sean Holland and others.