Tham khảo Tổng_Riemann

  1. ↑ Hughes-Hallett, Deborah; McCullum, William G. (2005). Calculus (ấn bản 4). Wiley. tr. 252. Đã bỏ qua tham số không rõ |displayauthors= (gợi ý |display-authors=) (trợ giúp) (Among many equivalent variations on the definition, this reference closely resembles the one given here.)
  2. 1 2 3 Hughes-Hallett, Deborah; McCullum, William G. (2005). Calculus (ấn bản 4). Wiley. tr. 340. So far, we have three ways of estimating an integral using a Riemann sum: 1. The left rule uses the left endpoint of each subinterval. 2. The right rule uses the right endpoint of each subinterval. 3. The midpoint rule uses the midpoint of each subinterval. Đã bỏ qua tham số không rõ |displayauthors= (gợi ý |display-authors=) (trợ giúp)
  3. 1 2 3 Ostebee, Arnold; Zorn, Paul (2002). Calculus from Graphical, Numerical, and Symbolic Points of View . tr. M-33. Left-rule, right-rule, and midpoint-rule approximating sums all fit this definition.