Cullen, M. J. P., Douglas, R. J., Roulstone, I. and Sewell, M. J. (2005) Generalized semi-geostrophic theory on a sphere. Journal Of Fluid Mechanics, 531. pp. 123-157.

Cullen, M.J.P., Douglas, R.J., Roulstone, I. and Sewell, M. J., (2003) Generalised semi-geostrophic theory on a sphere. JCMM Internal Report 138. UNSPECIFIED