A generalized normal form and formal equivalence of two-dimensional systems with quadratic zero approximation. II (Q2468707)

The authors derive normal forms to the systems \[ \dot x_1= \alpha x^2_1+ x_1x_2+ X_1(x_1, x_2),\quad\dot x_2= x_1x_2+ X_2(x_1, x_2) \] and \[ \dot x_1= \pm x_1x_2+ X_1(x_1, x_2),\quad\dot x_2= x^2_1+ X_2(x_1, x_2). \] For Parts I and III, see Zbl 1085.34034 and Zbl 1244.34060.