@inbook{NBERc3501,
 Crossref = "NBERingr72-1",
 title = "THEORETICAL IS SUES AND PRACTICAL ALTERNATIVES IN MODEL DESIGN",
 author = "Gregory K. Ingram and John F. Kain and J. Royce Ginn",
 BookTitle = "The Detroit Prototype of the NBER Urban Simulation Model",
 Publisher = "UMI",
 pages = "56-72",
 year = "1972",
 URL = "http://www.nber.org/chapters/c3501",
}
@book{NBERingr72-1,
 title = "The Detroit Prototype of the NBER Urban Simulation Model",
 author = "Gregory K. Ingram and John F. Kain and J. Royce Ginn",
 institution = "National Bureau of Economic Research",
 type = "Book",
 publisher = "UMI",
 year = "1972",
 URL = "http://www.nber.org/books/ingr72-1",
}