Erschienen in: DA FONSECA, Carlos M., ed. and others. A Panorama of Mathematics : Pure and Applied. Providence, Rhode Island: American Mathematical Society, 2016, pp. 115-126. Contemporary Mathematics. 658. ISSN 0271-4132. eISSN 1098-3627. ISBN 978-1-4704-1668-3. Available under: doi: 10.1090/conm/658
