Very important in cataloguing Dvor k works was and is Jarmil Burghauser. He did important biographical surveys and numbered Dvor k's works in chronological order.
Some works have other opus numbers put in brackets after the name.
Those are the numbers Dvor k gave them himself. He had a contract with the Berlin publisher Simrock, who was afraid that low opus numbers would not sell. Older work handed in by Dvor k was given a higher opus number by Simrock, which was next in line after the last published work. Of course this is only a start to perfection, so if you want to make submissions of any kind. Feel free to also leave any comments, or just say hi.