“…In [28], Yehia has introduced a method for constructing integrable conservative twodimensional mechanical systems whose second integral of motion is polynomial in velocities. This method appeared to be successful in constructing a great number of irreversible systems (involving gyroscopic forces) with a second integral quadratic (see, e.g., [29,30]), cubic [31] and quartic (see, e.g., [23] and [32][33][34][35][36]). In this method, the configuration space is not assumed to be the Euclidean plane.…”