Hi, welcome to Warhammer 40k! Thanks for your edit to the Tomb World page.
The source is Deathwatch: First Founding (RPG), pp. 82-83, as listed at the bottom of the page.
=Shas'o'Kais= Mobility, Technology, Firepower - In the name of the Greater Good; we will triumph. (talk) 06:41, August 21, 2013 (UTC)