more helpful sources provided by @santacml
https://danieltakeshi.github.io/2019/03/09/conv-matmul/ 10
https://towardsdatascience.com/backpropagation-in-a-convolutional-layer-24c8d64d8509 7
  
      
      github.com
  
  
    

vdumoulin/conv_arithmetic 4


  A technical report on convolution arithmetic in the context of deep learning