 His monograph "Smut Fungi of the World", published in 2012 by (APS Press) was described as “a culmination of more than 50 years of dedicated work and passion for smut fungi.” The nearly 1500 page monograph has been described as the "Holy Book of Smut Fungi", because it comprises the description of the 1700 known species with their synonyms, important literature, their host plants and over 3.500 illustrations of which 650 are the author's drawings of smutted plants.The third edition of his "Illustrated Genera of Smut Fungi" was published in 2013.In this edition, 104 recognized genera of smut fungi are presented, described and illustrated, compared to the second edition, in which 77 genera are identified.