Most of the Government Documents at Tech are shelved by SuDoc numbers.
Here is a SuDoc Tutorial:
Here is a list of government authors with the SuDoc agency symbol:
A Agriculture
AE National Archives and Records Administration
B Broadcasting Board of Governors
C Commerce Department
CC Federal Communications Commission
CR Civil Rights Commission
D Defense Department
E Energy Department
ED Education Department
EP Environmental protection Agency
FA Fine Arts Commission
FCA Farm Credit Administration
FHF Federal Housing Financing Board
FM Federal Mediation and Conciliation Service
FMC Federal Maritime Commission
FR Federal Reserve System Board of Governors
FT Federal Trade Commission
FTZ Foreign-Trade Zones Board
GA Government Accountability Office
GP Government Printing Office
GS General Services Administration
HE Health and Human Services Department
HH Housing and Urban Development Department
HS Homeland Security
I Interior Department
IC Interstate Commerce Commission
ID US Agency for International Development
ITC International Trade Commission
J Justice Department
JU Judiciary
L Labor Department
LC Library of Congress
LR National Labor Relations Board
MS Merit Systems Protection Board
NAS National Aeronautics and Space Administration
NC National Capital Planning Commission
NCU National Credit Union Administration
NF National Foundation on the Arts and the Humanities
NMB National Mediation Board
NS National Science Foundation
OP Overseas Private Investment Corporation
P United States Postal Service
PE Peace Corps
PM Personnel Management Office
PR President of the United States
PREX Executive Office of the President
PRVP Vice President of the United States
RR Railroad Retirement Board
S State Department
SBA Small Business Administration
SE Securities and Exchange Commission
SI Smithsonian Institution
SSA Social Security Administration
T Treasury Department
TD Transportation Department
TDA US Trade and Development Agency
VA Veterans Affairs Department
X and Y Congress