@incollection{MEM_2023_52_a12,
     author = {Vetseva, Evgeniya},
     title = {A problem-based approach in teaching progressions},
     booktitle = {},
     series = {Mathematics and Education in Mathematics},
     pages = {154--165},
     year = {2023},
     volume = {52},
     language = {bg},
     url = {http://geodesic.mathdoc.fr/item/MEM_2023_52_a12/}
}