Attached is the Sole Source Justification for the Firm-Fixed-Price Purchase Order for Maintenance of a Technical Advisory Group for United States Representation, pursuant to the authority of FAR 6.302... Attached is the Sole Source Justification for the Firm-Fixed-Price Purchase Order for Maintenance of a Technical Advisory Group for United States Representation, pursuant to the authority of FAR 6.302-1 Only one responsible source and no other supplies or services will satisfy agency requirements.