↑ Beckman, F. S.; Quarles, D. A., Jr. (1953). “On isometries of Euclidean spaces” (PDF). Proceedings of the American Mathematical Society. 4 (5): 810–815. doi:10.2307/2032415. JSTOR2032415. MR0058193. Let T be a transformation (possibly many-valued) of E n {\displaystyle E^{n}} ( 2 ≤ n < ∞ {\displaystyle 2\leq n<\infty } ) into itself. Let d ( p , q ) {\displaystyle d(p,q)} be the distance between points p and q of E n {\displaystyle E^{n}} , and let Tp, Tq be any images of p and q, respectively. If there is a length a > 0 such that d ( T p , T q ) = a {\displaystyle d(Tp,Tq)=a} whenever d ( p , q ) = a {\displaystyle d(p,q)=a} , then T is a Euclidean transformation of E n {\displaystyle E^{n}} onto itself.
Rudin, Walter (1991). Functional Analysis. International Series in Pure and Applied Mathematics. 8 (Second ed.). New York, NY: McGraw-Hill Science/Engineering/Math. ISBN 978-0070542365. OCLC 21163277.CS1 maint: ref=harv (link)
Narici, Lawrence; Beckenstein, Edward (2011). Topological Vector Spaces. Pure and applied mathematics (Second ed.). Boca Raton, FL: CRC Press. ISBN 978-1584888666. OCLC 144216834.
Schaefer, Helmut H.; Wolff, Manfred P. (1999). Topological Vector Spaces. GTM. 8 (Second ed.). New York, NY: Springer New York Imprint Springer. ISBN 978-1-4612-7155-0. OCLC 840278135.CS1 maint: ref=harv (link)
Trèves, François (ngày 6 tháng 8 năm 2006) [1967]. Topological vector spaces, distributions and kernels. Mineola, N.Y.: Dover Publications. ISBN 978-0486453521. OCLC 853623322.CS1 maint: ref=harv (link) CS1 maint: date and year (link)
