C. S. Jeffery, R. L. C. Starling, P. W. Hill, D. Pollacco: Cyclic and secular variation in the temperatures and radii of extreme helium stars. In: Monthly Notices of the Royal Astronomical Society. 321. Jahrgang, 2001, S.111, doi:10.1046/j.1365-8711.2001.03992.x, bibcode:2001MNRAS.321..111J.
C. S. Jeffery, R. L. C. Starling, P. W. Hill, D. Pollacco: Cyclic and secular variation in the temperatures and radii of extreme helium stars. In: Monthly Notices of the Royal Astronomical Society. 321. Jahrgang, 2001, S.111, doi:10.1046/j.1365-8711.2001.03992.x, bibcode:2001MNRAS.321..111J.