V. Formisano et P. Salinari, Low frequency plasma waves non linear interactions. Part I: The general dispersion relation, Laboratorio di Ricerca e Tecnologia per lo Studio del Plasma nello Spazio , LPS-70(5), 1970, pp. 1-20
Starting from a Vlasov-Maxwell sistem of equations, a correction is obtained to the linear theory of plasma waves. The results are valid for an infinite, homogeneous collisionless two component plasma immersed in an exthernal uniform magnetic field. It is also assumed that the weak turbolence existing has an interaction time much longer than the gyroperiod.