1. Adelman, M. A. (1969). Comment on the “H” concentration measure as a numbers-equivalent. The Review of Economics and Statistics, 51(1), 99–101.
2. Alfonso, A., & Venâncio, A. (2013). The relevance of commuting zones for regional spending efficiency. Working Paper 17/2013/DE/UECE/ADVANCE, Department of Economics, School of Economics and Management, Technical University of Lisbon. http://pascal.iseg.utl.pt/~depeco/wp/wp172013.pdf 2014-01-10
3. Arriaga, E. E. (1970). A new approach to the measurements of urbanization. Economic Development and Cultural Change, 18(2), 206–218.
4. Arriaga, E. E. (1975). “Selected measures of urbanization”, Chap. II. In S. Goldstein, D. F. Sly (Eds.), The measurement of urbanization and projection of urban population, Working Paper 2, International Union for the scientific study of population. Committee on urbanization and population redistribution. Ordina Editions, Dolhain, Belgium.
5. Boix, R., & Galleto, V. (2006). Identificación de Sistemas Locales de Trabajo y Distritos Industriales en España. Dirección General de Política de la Pequeña y Mediana Empresa, Ministerio de Industria, Comercio y Turismo.