SMIT JJ (1977) The Night Heron already bred in The Netherlands in the thirties. LIMOSA 50 (1): 6-9.

It was assumed that in 1946 the Night Heron (Nycticorax nycticorax) was found breeding in The Netherlands for the first time since 1876. However, now records have been found that the species bred already as early as 1933 and most of the following years in the Biesbosch and its surroundings Black-crowned Night Heron Nycticorax nycticorax

[free pdf] [dutch summary]