Kingdom of Bulgaria 1945 - Immediate Post-War Transitional Type - Uncommon

This is a fascinating and historically significant document. It is a passport issued by the Kingdom of Bulgaria (Царство България / Royaume de Bulgarie) during a period of immense political upheaval at the end of World War II.
The passport is issued ВЪ ИМЕТО НА НЕГОВО ВЕЛИЧЕСТВО СИМЕОН II, ЦАР НА БЪЛГАРИТѢ (In the name of His Majesty Simeon II, King of the Bulgarians).
* Historical Context: Simeon II (born 1937) was the last Tsar of Bulgaria. He was a child king who ascended to the throne in 1943. Bulgaria had switched sides in WWII and was under the control of the communist-dominated Fatherland Front government, operating under the supervision of the Allied Control Commission (Soviet command) in 1945, though the monarchy was not formally abolished until a referendum in September 1946. This passport represents the final phase of the monarchy.

The Significance of the Date and Location (October 28, 1945, in Belgrade):
This document was issued after the Soviet-backed Fatherland Front coup in Bulgaria (September 9, 1944) and the end of World War II (May 1945).
1. Post-War/Communist Transition: The government in Sofia was already under heavy Soviet influence, though the monarchy had not been formally abolished. The passport represents the last days of the old political order's diplomatic presence.
2. Bulgaria-Yugoslavia Relations: Bulgaria and Yugoslavia (under Tito's communists) had recently experienced a period of extreme tension during the war (Bulgarian occupation of parts of Yugoslavia). However, after the Soviet invasion of Bulgaria in 1944, the new Fatherland Front government immediately began establishing friendly relations with Tito's communist-led Yugoslav Partisans (Source 2.3).
3. The Legation in Belgrade: The issuance of this passport by the Bulgarian Legation in Belgrade (the capital of Yugoslavia) in late 1945 shows that Bulgaria still maintained a diplomatic presence despite the shift in power. The Legation's role would have been critical in managing the movement of Bulgarian nationals, like Mr. Zolakoff, into the newly-formed Federal People's Republic of Yugoslavia, indicating a specific (and likely government-approved) reason for his travel to Yugoslavia.
4. Travel to Yugoslavia: The fact the passport is only explicitly valid for "Yugoslavia" suggests that the bearer was likely a Bulgarian citizen residing or needing to travel specifically within Yugoslavia, perhaps as part of the new cooperative relationship between the two states.