US lawFederal (United States)RegulationsTitle 40 CFR — Protection of EnvironmentChapter I — ENVIRONMENTAL PROTECTION AGENCYPart 52 — APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANSSubpart A — General Provisions52.1840 C.F.R. § 52.18Abbreviations.Last amended: 2016Year: 2026Length: 22 wordsOfficial source Cite as 40 C.F.R. § 52.18 (2026)Abbreviations used in this part shall be those set forth in part 60 of this chapter. [38 FR 12698, May 14, 1973]Previous40 C.F.R. § 52.17Next40 C.F.R. § 52.20