CHAPTER 9 - REQUIRED SOURCES OF SUPPLIES AND SERVICES 9-1. Required Sources9-2. UNICOR/Federal Prison Industries9-3. AbilityOne9-4. Computer Hardware, Enterprise Software and Solutions (CHESS)9-5. U.S. Navy’s Spiral 4 Contracts9-6. DLA Document Services9-8. Non-Mandatory Sources of Supply9-9. Sustainable Procurement9-10. Commercial PlatformsParent topic: APPENDIX - EE DEPARTMENT OF THE ARMY GOVERNMENT PURCHASE CARD OPERATING PROCEDURES