Early design documents for Deus Ex (including its early precursors Shooter and Shooter: Majestic Revelations) provide information on the game's development history, as well as cut or prerelease content not present in the final game. Some of the content in later design documents were incorporated into the Deus Ex Bible.
The contents of only a few design documents are known to the general public in substantial form. A number of design documents were contributed by Warren Spector to the collections of the Briscoe Center for American History at the University of Texas at Austin, but most of the collection has not been publicly released.
Cover page of design document v.5.3e (Shooter: Majestic Revelations)
Cover page of design document v.9.9
Cover page of design document v.13.12
Design documents in a display case (Game Masters Exhibition, June 28, 2012 to October 28, 2012, Melbourne, Australia)
Closeup of two documents in the display case
April 14, 1998 design document (Game Masters Exhibition). The subtitle reads "The game formerly known as 'Shooter'" and "Roleplaying in a World of Secrets, Lies and Conspiracies".
Warren Spector's presentation at GDC 2017, showing an image of design document 13.12
↑The date 12/14/1999 is displayed in the version of the file shown in Spector's presentation at GDC 2017 (see image). Note that the version of the file that was made public lists 1999 as the year, but does not display a specific date (note that the date shown on the cover and footer of the available .doc version is not the true date, because it is an auto-updating "today's date" field.).