The interpretation of the imaginary unit as the ratio of two perpendicular vectors was proposed by Hermann Grassmann in the foreword to his Ausdehnungslehre of 1844; later William Clifford realized that this ratio could be interpreted as a bivector. Hestenes, David (1996). "Grassmann's Vision"(PDF). In Schubring, G. (ed.). Hermann Günther Graßmann (1809–1877). Boston Studies in the Philosophy of Science. Vol. 187. Springer. pp. 243–254. doi:10.1007/978-94-015-8753-2_20. ISBN978-90-481-4758-8.
The interpretation of the imaginary unit as the ratio of two perpendicular vectors was proposed by Hermann Grassmann in the foreword to his Ausdehnungslehre of 1844; later William Clifford realized that this ratio could be interpreted as a bivector. Hestenes, David (1996). "Grassmann's Vision"(PDF). In Schubring, G. (ed.). Hermann Günther Graßmann (1809–1877). Boston Studies in the Philosophy of Science. Vol. 187. Springer. pp. 243–254. doi:10.1007/978-94-015-8753-2_20. ISBN978-90-481-4758-8.
Zill, Dennis G.; Shanahan, Patrick D. (2003). A first course in complex analysis with applications. Boston: Jones and Bartlett. pp. 24–25. ISBN0-7637-1437-2. OCLC50495529.