4U 0115 + 63: phase lags and cyclotron resonant scatteringC. Ferrigno, M. Falanga, E. Bozzo, P. A. Becker, D. Klochkov and A. SantangeloA&A, 532 (2011) A76DOI: https://doi.org/10.1051/0004-6361/201116826