251.102 - Authorization to use Government supply sources
(e) When authorizing contractor use of Government supply sources, follow the procedures at PGI 251.102 .
(3)(ii) The contracting officer may also authorize the contractor to use the DD Form 1155 when requisitioning from the Department of Veterans Affairs.
(f) The authorizing agency is also responsible for promptly considering requests of the DoD supply source for authority to refuse to honor requisitions from a contractor that is indebted to DoD and has failed to pay proper invoices in a timely manner.

251.107 - Contract clause
Use the clause at 252.251-7000 , Ordering From Government Supply Sources, in solicitations and contracts which include the clause at FAR 52.251-1, Government Supply Sources.
See DoD Class Deviation 2013-O0012, Authorization for Contractors to Use Government Supply Sources in Support of Operation Enduring Freedom, issued on April 24, 2013. This deviation encourages contracting officers to authorize contractors (including contractors with fixed-price contracts) to use appropriate Government supply sources, including DLA (for construction materials) and GSA Central Asia and South Caucasus Supply Catalog under the GSA Global Supply Program, in performance of contracts in support of Operation Enduring Freedom. This constitutes a deviation from the policy at FAR 51.101. This class deviation remains in effect until incorporated in the DFARS or otherwise rescinded.