@inbook{NBERc9942,
 Crossref = "NBERaesm73-4",
 title = "Time-Varying Regression Coefficients: A Mixed Estimation Approach and Operational Limitations of The General Markov Structure",
 author = "J Philip Cooper",
 BookTitle = "Annals of Economic and Social Measurement, Volume 2, number 4",
 Publisher = "NBER",
 pages = "521-526",
 year = "1973",
 month = "October",
 URL = "http://www.nber.org/chapters/c9942",
}
@book{NBERaesm73-4,
 title = "Annals of Economic and Social Measurement, Volume 2, number 4",
 author = "Sanford V. Berg, editor",
 institution = "National Bureau of Economic Research",
 type = "Book",
 publisher = "NBER",
 year = "1973",
 URL = "http://www.nber.org/books/aesm73-4",
}