Key points are not available for this paper at this time.
Yujiro Kawamata, Crepant Blowing-Up of 3-Dimensional Canonical Singularities and Its Application to Degenerations of Surfaces, Annals of Mathematics, Second Series, Vol. 127, No. 1 (Jan., 1988), pp. 93-163
Yūjirō Kawamata (Fri,) studied this question.