1930: Alphonse Delahaye, Vade-Mecum for referees

Vade-Mecum for referees written by the Belgian referee Alfonse Delahaye in 1930.
Alfonse Delahaye was on of the best referees of the period 20's-40's. After the London 1948, Olympic Games, as member of the International Water Polo Board, along with Jan de Vries of Holland, in 1950 addopted the discontinuance of the "non moving rule", a fact that contributed to the radical change of playing style.
The book has been translated by the Catalan Swimming Federation and distributed in 1930 for free.