http://vak.rutgers.edu/Articles_about_VAK/%D0%A7%D0%B5%D0%BB%D0%BE%D0%B2%D0%B5%D0%BA_%D0%BA%D0%BE%D1%82%D0%BE%D1%80%D1%8B%D0%B8%CC%86_%D0%BF%D0%BE%D0%BC%D0%BE%D0%B3_%D0%AD%D0%B8%CC%86%D0%BD%D1%88%D1%82%D0%B5%D0%B8%CC%86%D0%BD%D1%83.pdf