On the NP-Hardness of Edge-Deletion and -Contraction Problems
Discrete Applied Mathematics, Vol.6, No.1, pp.63-78, May 1983

Edge-Connectivity Augmentation Problems
Journal of Computer and System Sciences, Vol.35, No.1, pp.96-144,
August 1987

A Minimum 3-Connectivity Augmentation of a Graph
Journal of Computer and System Sciences, Vol.46, No.1, pp.91-128,
February 1993