Tham khảo Phủ_(tô_pô)

  1. 1 2 3 Manetti (2014), tr. 71, Definition 4.30
  2. Manetti (2014), tr. 71, Definition 4.31
  3. Manetti (2014), tr. 71, Definition 4.30
  4. Manetti (2014), tr. 134, Definition 7.12
  5. Bott; Tu (1982), tr. 111