@inbook{NBERc2690,
 Crossref = "NBERtroy57-1",
 title = "Extent of Union Organization, by State and Region, 1939 and 1953",
 author = "Leo Troy",
 BookTitle = "Distribution of Union Membership among the States, 1939 and 1953",
 Publisher = "NBER",
 pages = "17-27",
 year = "1957",
 URL = "http://www.nber.org/chapters/c2690",
}
@book{NBERtroy57-1,
 title = "Distribution of Union Membership among the States, 1939 and 1953",
 author = "Leo Troy",
 institution = "National Bureau of Economic Research",
 type = "Book",
 publisher = "NBER",
 year = "1957",
 URL = "http://www.nber.org/books/troy57-1",
}