HELLEBREKERS WPJ (1959) Oölogische and nidologische communications: 1957-II and 1958: More or less regular occurrence of two broods in the ackcap Sylvia atricapilla. LIMOSA 32 (3): 155-155.
Blackcap Sylvia atricapilla More or less regular occurrence of two broods in the ackcap Sylvia atricapilla
