@article{BraunKummerXu2009,
  author    = {Uwe Braun and Volker Kummer and B. Xu},
  title     = {Taxonomy and nomenclature of powdery mildew fungi : erysiphe asclepiadis, E. robiniicola and Golovinomyces caulicola},
  year      = {2009},
}