Design and Update of a Classification System: The UCSD Map of Science
Börner, K., Klavans, R., Patek, M., Zoss, A.M., Biberstine, J.R., Light, R.P., Larivière, V., Boyack, K.W. (2012). Design and Update of a Classification System: The UCSD Map of Science. PLOS ONE, 7(7): e39464.