Pereverzev, G. (2001). Paraxial WKB Description of Short Wavelength Eigenmodes in a Tokamak. Physics of Plasmas, 8, 3664-3672. Retrieved from http://scitation.aip.org/getpdf/servlet/GetPDFServlet?filetype=pdf&id=PHPAEN000008000008003664000001&idtype=cvips.