@incollection{MEM_2023_52_a9,
     author = {Petrov, Philip and Ninova, Julia},
     title = {In memoriam of {Prof.} {Ivan} {Gantchev} {Donev}},
     booktitle = {},
     series = {Mathematics and Education in Mathematics},
     pages = {101--133},
     year = {2023},
     volume = {52},
     language = {bg},
     url = {http://geodesic.mathdoc.fr/item/MEM_2023_52_a9/}
}