ඉකරස් 82 (1): 36–49. doi:10.1016/0019-1035(89)90021-3. "densities obtained by this procedure are in reasonable agreement with intuitive expectations of densities near 1 g/cm3, the uncertainties in several parameters and assumptions expand the error bars so far as to make the constraints on the density uniformative ... suggestion that cometary nuclei tend to by very fluffy, ... should not yet be adopted as a paradigm of cometary physics.".