Fledgling (Poletarac) was "an illustrated collection of educational texts (poems, short stories, riddles)" which ran in the mid-70s 80s in Serbia, edited by Dušan Radovic. "The texts explain different subjects and natural phenomena and teach children about famous people (scientists, writers, painters) and their works."

My original Serbian Sesame Street is a personal favorite, and thanks to my friend billyjane I actually now own a bunch of issues of the magazine, though as in the first post these scans come from the incredible International Children's Digital Library. (The page size is at least 11" x 17" so scanning is not a simple job.) One more sequel to follow.

[May 25 update: Jelena kindly got in touch with some corrections: "Dusan Radovic was an editor but not illustrator (he was also a poet and journalist and overall major influence on our Yugoslav generation growing up). Most of the illustrations were done by Dusan Petricic (unofficial Facebook page).
Poletarac was also a TV show, authored by Timothy John Byford (you can find some clips on Youtube).]"

I'm on the case.