@inbook{NBERc4663,
 Crossref = "NBERcomm23-1",
 title = "Changes in Employment in the Principal Industrial Fields: January 1, 1920 to March 31, 1922",
 author = "Willford I. King",
 BookTitle = "Business Cycles and Unemployment",
 Publisher = "NBER",
 pages = "80-100",
 year = "1923",
 URL = "http://www.nber.org/chapters/c4663",
}
@book{NBERcomm23-1,
 title = "Business Cycles and Unemployment",
 author = "",
 institution = "National Bureau of Economic Research",
 type = "Book",
 publisher = "NBER",
 year = "1923",
 URL = "http://www.nber.org/books/comm23-1",
}