Near-infrared and optical observations of galactic warps: a common, unexplained feature of most discsA. Guijarro, R. F. Peletier, E. Battaner, J. Jiménez-Vicente, R. de Grijs and E. FloridoA&A, 519 (2010) A53DOI: https://doi.org/10.1051/0004-6361/201014506
