To find this information, you might try:
* Searching for him on Wikipedia or other biographical databases: Look for a page specifically about Dragutin Vunak, or search for him within the context of his profession (e.g., if he's a martial arts instructor, search for his name and "martial arts").
* Checking martial arts websites and forums: If he's involved in martial arts, there might be information about him on these sites.
* Contacting a martial arts organization he's associated with: If you know which organization he belongs to, they might have biographical information available.
Please provide more context about Dragutin Vunak to help me find the information you need.