Gledhill, TM;    Chrysostomou, A;    Hough, JH;    Yates, JA;      (2001)    Axisymmetry in protoplanetary nebulae: using imaging polarimetry to investigate envelope structure.                   Monthly Notices of the Royal Astronomical Society , 322  (2)   321 - 342.    10.1046/j.1365-8711.2001.04112.x <https://doi.org/10.1046/j.1365-8711.2001.04112.x>.       Green open access