Multi-Mode and Non-Standard Classical Cepheids in the Magellanic System
  We present a sample of the most interesting classical Cepheids selected from the OGLE collection of classical Cepheids in the Magellanic System. The main selection criterion for this sample was the presence of non-standard, unique pulsational properties.   The sample contains the first known double-mode Cepheid pulsating in the second- and third-overtone modes and a large number of objects with non-radial modes excited. We also found Cepheids revealing Blazhko-like light curve modulation, objects ceasing pulsations or showing atypical shapes of their light curves. Additionally, the status of several triple mode classical Cepheids is updated based on OGLE-IV photometry extending the time baseline to 15 years. 
I. Soszynski, A. Udalski, M. K. Szymanski, R. Poleski, P.   Pietrukowicz, S. Kozlowski, P. Mroz, L. Wyrzykowski, D. Skowron,...
astro-ph.SR