Bollen, Laurens ; van Kampen, Paul ; Baily, Charles.. Bollen , L , van Kampen , P , Baily , C , Kelly , M & De Cock , M 2017 , ' Student difficulties regarding symbolic and graphical representations of vector fields ' , Physical Review Physics Education Research , vol. 13 , no. 2 , 020109 . https://doi.org/10.1103/PhysRevPhysEducRes.13.020109.
,
2017