Fishes of the World by Joseph S. Nelson is a standard reference for fish systematics. Now in its fifth edition (2016), the work is a comprehensive overview of the diversity and classification of the 30,000-plus fish species known to science. The fourth edition was the first to incorporate the wide use of DNA analysis, revising many earlier classifications. The first edition appeared in 1976, the second in 1984, the third in 1994 (John Wiley & Sons, ISBN 0-471-54713-1), the fourth in March 2006 (ISBN 0-471-25031-7), and the fifth in April 2016 (ISBN 9781118342336).