Solomon, David J., and Bo-Christer Björk. "
A study of open access journals using article processing charges."
Journal of the American Society for Information Science and Technology 63, no. 8 (2012): 1485-1495.
Sowa, John F.. "
Ontology, Metadata, and Semiotics." In
Lecture Notes in Computer Science, 55-81. Springer, Berlin, Heidelberg.