Unconventional superconductivity in ultrathin superconducting NbN films studied by scanning tunneling spectroscopy. - Noat, Y.; Cherkez, V.; Brun, C.; Cren, T.; Carbillet, C.; Debontridder, F.; Ilin, K.; Siegel, M.; Semenov, A.; Hübers, H.-W.; Roditchev, D. (Physical Review B: Condensed Matter & Materials Physics, 2013)