Occurrence conditions for two-dimensional Borromean systems Artem G. Volosniev, Dmitri V. Fedorov, Aksel S. Jensen and Nikolaj T. Zinner Eur. Phys. J. D, 67 5 (2013) 95 Published online: 07 May 2013 DOI: 10.1140/epjd/e2013-30693-5