@incollection{MEM_2021_50_a29,
     author = {Zhelyazkova, Tsvetelina and Boykina, Dobrinka},
     title = {Using a heuristic approach in maths education in 6th - 7th grade},
     booktitle = {},
     series = {Mathematics and Education in Mathematics},
     pages = {252--260},
     year = {2021},
     volume = {50},
     language = {bg},
     url = {http://geodesic.mathdoc.fr/item/MEM_2021_50_a29/}
}