 On August 3, 1611 Kepler’s wife, Barbara Müller, died. In 1612 he moved to Linz, in Upper Austria, and became a professor at the Landschaftsschule. There, he served as Mathematician of the Upper Austrian Estates from 1612 to 1628. In 1613, he married Susanne Reuttinger, with whom he had six children. In 1615, he completed the mathematical works Stereometria doliorum and Messekunst Archimedis. At the end of 1617 Kepler successfully defended his mother, who had been accused of witchcraft. In 1619 he published his principal philosophical work, the Harmonice mundi (=HM), and wrote, partially at the same time, the Epitome astronomiae copernicanae (=EAC). In 1624 Kepler continued his investigations on mathematics, publishing his work on logarithms (Chilias logarithmorum…).