@techreport{US-Environmental-Protection-Agency-EPA-2010-4073,
  author = {US Environmental Protection Agency (EPA)},
  title = {Nonroad Engine Population Estimates},
  institution = {US Environmental Protection Agency (EPA)},
  year = {2010},
  month = {jul},
  number = {NR-006e},
  url = {https://nepis.epa.gov/Exe/ZyNET.exe/P10081T6.TXT?ZyActionD=ZyDocument&Client=EPA&Index=2006%20Thru%202010&Docs&Query&Time&EndTime&SearchMethod=1&TocRestrict=n&Toc&TocEntry&QField&QFieldYear&QFieldMonth&QFieldDay&IntQFieldOp=0&ExtQFieldOp=0&XmlQuery&File=D%3A%5Czyfiles%5CIndex%20Data%5C06thru10%5CTxt%5C00000019%5CP10081T6.txt&User=ANONYMOUS&Password=anonymous&SortMethod=h%7C-&MaximumDocuments=1&FuzzyDegree=0&ImageQuality=r75g8/r75g8/x150y150g16/i425&Display=hpfr&DefSeekPage=x&SearchBack=ZyActionL&Back=ZyActionS&BackDesc=Results%20page&MaximumPages=1&ZyEntry=1&SeekPage=x&ZyPURL},
  keywords = {Gasoline, Methane (Natural Gas), Engine Testing and Performance, Recreational},
}