Ka cika wannan magana: Milanković ya yi shekara biyu yana shirya da kuma rubuta "Canon". An gabatar da rubutun don bugawa a ranar 2 ga Afrilu 1941 <unk> kwanaki hudu kafin harin Nazi Jamus da kawayenta kan Masarautar Yugoslavia. A cikin
bombardment na Belgrade a ranar 6 ga Afrilu 1941, an lalata gidan buga takardu inda ake buga aikinsa; duk da haka, kusan dukkanin takaddun takarda da aka buga sun kasance ba tare da lalacewa ba a cikin shagon buga takardu. Bayan nasarar mamaye Serbia a ranar 15 ga Mayu 1941, jami'an Jamus biyu da ɗaliban ilimin ƙasa sun zo Milanković a gidansa kuma sun kawo gaisuwa daga Farfesa na Freiburg. Milanković ya ba su cikakken kwafin "Canon" don aikawa zuwa Soergel, don tabbatar da cewa za a adana aikinsa. Milanković bai shiga cikin aikin jami'ar ba a lokacin mamayewa, kuma bayan yakin an dawo da shi a matsayin farfesa.