In this chapter, the following documents are incorporated by reference. Documents Incorporated. EPA Method 2 (40 CFR Part 60, Appendix A-1, Section 10.3, as amended). EPA Method 3A (40 CFR Part 60, Appendix A, as amended). EPA Method 3C (40 CFR Part 60, Appendix A, as amended). EPA Method 10 (40 CFR Part 60, Appendix A, as amended). EPA Method 18 (40 CFR Part 60, Appendix A, as amended). EPA Method 21 (40 CFR Part 60, Appendix A, as amended). EPA Method 25 (40 CFR Part 60, Appendix A, as amended). EPA Method 25C (40 CFR Part 60, Appendix A, as amended). ASTM D6522-11, “Standard Test Method for Determination of Nitrogen Oxides, Carbon Monoxide, and Oxygen Concentrations in Emissions from Natural Gas-Fired Reciprocating Engines, Combustion Turbines, Boilers, and Process Heaters Using Portable Analyzers, December 1, 2011. ASTM D6522-20, “Standard Test Method for Determination of Nitrogen Oxides, Carbon Monoxide, and Oxygen Concentrations in Emissions from Natural Gas-Fired Reciprocating Engines, Combustion Turbines, Boilers, and Process Heaters Using Portable Analyzers, June 1, 2020.