1. Berthoud, R., 1976, Where are London's poor? Greater London Intelligence Quarterly , Vol. 36, 5–12.
2. Birdsall, S. S., 1980, Analysis of population age balance. The Professional Geographer , Vol. 32, 467–470.
3. Bogue, D. J., 1969. Principles of Demography. New York: John Wiley & Sons.
4. Clark, A. R., 1975, Selected demographic components of the non-white population of Baltimore: a comment. The Middle Atlantic , Vol. 6, 75–82.
5. Coulson, M. R. G., 1968, The distribution of population age structures in Kansas City. Annals, Association of American Geographers , Vol. 58, 155–176.