Mathematics: Easy and Hard. Why?
Crossref DOI link: https://doi.org/10.1007/s00283-017-9718-x
Published Online: 2017-08-30
Published Print: 2017-09
Update policy: https://doi.org/10.1007/springer_crossmark_policy
Booß-Bavnbek, Bernhelm http://orcid.org/0000-0002-8865-7298
License valid from 2017-08-30