Text this: Boar semen preservation II : proceedings, second International Conference on Boar Semen Preservation / dedicated to the memory of Kjell Larsson ; general editors, Lawrence A. Johnson, Detlef Rath ; associate editors, Karl F. Weitze, Ben Colenbrander ; held at United Sttes Department of Agriculture, Agricultural Research Service, Beltsville, Maryland, USA, August, 1990.