Robert Ganian, Ronald de Haan, Iyad Kanj, Stefan Szeider. On Existential MSO and its Relation to ETH. 41st International Symposium on Mathematical Foundations of Computer Science (MFCS 2016) (Piotr Faliszewski and Anca Muscholl and Rolf Niedermeier), volume 58 of Leibniz International Proceedings in Informatics (LIPIcs), pages 42:1-42:14, 2016, Schloss Dagstuhl–Leibniz-Zentrum fuer Informatik.