@inbook{NBERc2124,
 Crossref = "NBERuniv62-1",
 title = "Invention and Innovation in the Petroleum Refining Industry",
 author = "John L. Enos",
 BookTitle = "The Rate and Direction of Inventive Activity: Economic and Social Factors",
 Publisher = "NBER",
 pages = "299-322",
 year = "1962",
 URL = "http://www.nber.org/chapters/c2124",
}
@book{NBERuniv62-1,
 title = "The Rate and Direction of Inventive Activity: Economic and Social Factors",
 author = "Harold M. Groves, Chairman, Universities-National Bureau Committee for Economic Research",
 institution = "National Bureau of Economic Research",
 type = "Book",
 publisher = "NBER",
 year = "1962",
 URL = "http://www.nber.org/books/univ62-1",
}