@booklet{geo,
  author={Facultat de Matemàtiques i Estadística (UPC)},
  title={Apunts Geometría afí i euclidiana},
  url={https://drive.google.com/file/d/1V1TodeUpnjbe-JKKufW_Qe37EIHXZAUN/view}
}

@booklet{multi,
  author={Òscar Benedito, Ernesto Lanchares, Miquel Ortega},
  title={Álgebra Multilineal y Geometría Proyectiva},
  organization={ApuntsFME},
  pages={11},
  url={https://apuntsfme.gitlab.io/pdfs/segon/algebra_multilineal_y_geometria.pdf},
  year={2018}
}

@online{mathe,
  title={Cross product: matrix transformation identity},
  url={https://math.stackexchange.com/questions/859836/cross-product-matrix-transformation-identity}
}