Volume 4 contains identification keys, detailed descriptions, colour photographs, drawings and distribution maps of 67 northern European species of Tricholoma. The authors have been working on this project for more than 20 years, and have visited almost all corners of Europe. Numerous field trips have been supplemented with type studies, molecular phylogenetic analyses and discussions with many other experts. This publication will stand as one of the most important tools and references in the study of European Tricholomas for both amateurs and professionals for many years.