Zielinski, P., J. Zielisnki, and J. Banbura. “Selfish Behaviour of Juvenile Barn Swallows Hirundo Rustica Intruding in Active Nests”. Ornis Fennica, vol. 72, no. 2, July 1995, pp. 89–90, https://ornisfennica.journal.fi/article/view/133419.