Immanuel Kant
Kant developed his moral philosophy in three works: "Groundwork of the Metaphysic of Morals" (1785), "Critique of Practical Reason" (1788), and "Metaphysics of Morals" (1797).
Gustav Hartenstein
He extended Herbart's thinking in the works entitled:
Also, he was the author of a 12–volume edition of Herbart's works, titled "Johann Friedrich Herbart's sämmtliche werke" (1850–52). In 1867 he published an edition of Immanuel Kant's collected works; "Immanuel Kant's sämmtliche Werke" (8 volumes).