Relating Galaxy Cluster X-Ray Luminosities to Gravitational Masses in   Wide Angle Surveys
  It is shown that galaxy cluster surveys selecting clusters by their X-ray luminosity effectively select by cluster mass. It is shown that a selection based solely on Abell galaxy richness is less efficient in terms of mass. Furthermore the empirical X-ray luminosity - gravitational mass relation and its scatter is quantified and the relation is compared to predicted relations. 
Thomas H. Reiprich, Hans Boehringer (MPE)