Lilya Budaghyan Tor Helleseth New Perfect Nonlinear Multinomials over Ffor Any Odd Prime p. 403-414 2008 SETA http://dx.doi.org/10.1007/978-3-540-85912-3_35 conf/seta/2008 db/conf/seta/seta2008.html#BudaghyanH08