National versus International Mergers in Unionized Oligopoly
Kjell Erik Lommerud, Odd Rune Straume, Lars Sorgard
Rand Journal of Economics, vol. 37, 2006, p. 212-233.

Downstream Merger with Upstream Market Power
Kjell Erik Lommerud, Odd Rune Straume, Lars Sorgard
European Economic Review, vol. 49, 2005, p. 717-743.