The author calls attention to previous work with related results, which has escaped scrutiny before the publication of the article "Nonlinear quantum evolution with maximal entropy production", Phys.Rev. A63, 022105 (2001).In a recently published paper [1], I propose a nonlinear extension of the nonrelativistic Liouville-von Neumann equation, which incorporates both the unitary propagation of pure quantum states and the second principle of thermodynamics. Shortly after this work was approved for publication, it was brought to my attention [2] that a closely related undertaking on the subject was reported about two decades ago by G.P. , and later also by Korsch et al. [10,11]. The present Addendum is intended to acknowledge and correct this oversight, and to provide a few brief observations on the relation between these works and the results presented in [1].In ref.[3], Beretta et al. proposed that the dynamical principle of quantum theory be replaced by a postulated nonlinear equation of motion which is, algebraically, a generalization of Eq.(24) in [1] (see also Eq.(91)). General properties of this equation are also presented in an axiomatic framework, particularly with regard to the nature of nondissipative and equilibrium states (see also [4]). Unfortunately, the applicability of the theory was hindered by a number of mathematical difficulties, e.g., by lack of a definitive proof of the positivity of the evolution. A well-behaved example was given later for the two-level system in interaction with an external field [5]. Such problems notwithstanding, it was argued [6,7] that the proposed nonlinear evolution drives the density matrix along a direction of steepest entropy ascent under given constraints, and ref.[7] provides a notable theorem on exact, generalized Onsager reciprocity, not restricted to the near-equilibrium regime. The stability of thermodynamic equilibrium states has also been discussed [8], with reference to (but not limited to the context of) the postulated nonlinear dynamics. More recently, Korsch et al. studied a family of closely related dissipative dynamics [9], and also derived explicit solutions for a driven harmonic oscillator by Lie-algebra techniques [10].Beretta's confidence in the physicality of his construction seems to find vindication after all. In ref.[1] the theory is formulated in terms of state operators γ associated to the density matrix ρ [ρ = γγ + ] and the equation of motion is derived from a variational principle which observes the principles of quantum mechanics and the fundamental laws of thermodynamics. The existence and uniqueness of the solutions for ρ follow from the equation of motion for γ, and the positivity of the evolution is guaranteed by construction. The reader can also find alternative proofs for the fundamental properties of the equation of motion, a derivation of a near-equilibrium limit, exact to first-order deviations of γ from the equilibrium state, as well as a proof of the equivalence between symmetry covariance, conservation laws and associated com...