http://services.igi-global.com/resolvedoi/resolve.aspx?doi=10.4018/978-1-4666-2488-7.ch012
https://linkinghub.elsevier.com/retrieve/pii/S1571066104800902
http://www.journals.cambridge.org/abstract_S095679680000157X
https://www.cambridge.org/core/product/identifier/S0956796800001465/type/journal_article
http://www.journals.cambridge.org/abstract_S0956796800001143
http://www.journals.cambridge.org/abstract_S0960129500001547