UPDATE: Thanks for the comments, Anon:
Actually, Yugoslavia was composed of more republics, so the label is wrong. There are Serbian, Slovenian and other Mandrake editions. This one is Serbian, and there are many more, starting from the 1930s when Mandrake became highly popular in Serbia.
First Sunday strip S001 - The Hidden Kingdom of Murderers 02-03-1935 to 05-26-1935 I have only 3 pages. These are hard to find or come by. So if anybody gets any vintage strips please scan them.
Found this Yugoslavian Mandrake magazine having the full Sunday and some more:
Here is the full book cover to cover. Thanks to a Yugoslavian friend "Fantom"
Download Comic Book Here