"Wojna Światowa". Historia Polski. Originaali arhiivikoopia seisuga 31. detsember 2007. Vaadatud 24. augustil 2008.
web.archive.org
"Wojna Światowa". Historia Polski. Originaali arhiivikoopia seisuga 31. detsember 2007. Vaadatud 24. augustil 2008.
youtube.com
Andrzej Kunert in "Wrzesień 1939 9/19 - Bzura" claims that at least one pivotal attack was cancelled because, while marching, the soldiers were asleep because they have not slept for a few days. This led to the loss of momentum. URL:https://www.youtube.com/watch?v=x5QLw_zyMgo .