A warped accretion disc in PX And ?
  We have undertaken a photometric study of the SW Sex star, PX And. We clearly identify a negative superhump signal which might be regarded as the signature of a nodal precessing disc, possibly warped. PX And is also observed to possess highly variable eclipse depth and we discuss two possible explanations. 
H.M.J. Boffin, V. Stanishev, Z. Kraicheva, V. Genkov