Pairs of Bilinear and Quadratic Equations in a Finite Field. A. Duane Porter (1966) Monatshefte für Mathematik
Primitive free quartics with specified norm and trace Stephen D. Cohen, Sophie Huczynska (2003) Acta Arithmetica
Primitive roots and powers among values of polynomials over finite fields. Stephen D. Cohen (1984) Journal für die reine und angewandte Mathematik