Halmos, Paul R. (1970). "Finite-dimensional Hilbert spaces". Amer. Math. Monthly. 77 (5): 457–464. doi:10.2307/2317378. JSTOR2317378.
Ziemer, William P.; Wheeler, William H.; Moolgavkar; Halmos, Paul R.; Ewing, John H.; Gustafson, William H. (1976). "American mathematics from 1940 to the day before yesterday". Amer. Math. Monthly. 83 (7): 503–516. doi:10.2307/2319347. JSTOR2319347.
Halmos, Paul R. (1970). "Finite-dimensional Hilbert spaces". Amer. Math. Monthly. 77 (5): 457–464. doi:10.2307/2317378. JSTOR2317378.
Ziemer, William P.; Wheeler, William H.; Moolgavkar; Halmos, Paul R.; Ewing, John H.; Gustafson, William H. (1976). "American mathematics from 1940 to the day before yesterday". Amer. Math. Monthly. 83 (7): 503–516. doi:10.2307/2319347. JSTOR2319347.