 Refracting systems (details), University of Tennessee physics teaching resource

Publisher: University of Tennessee physics teaching site.

Online text: labs.phys.utk.edu/mbreinig/phys421/modules/m3/Refracting%20systems%20details.html

Cited passages: Refracting systems (details), definition of principal planes, unit lateral magnification, and final imaging equation; Refracting systems (details), principal-plane definition and final paragraph on object/image distances; University of Tennessee physics teaching resource, Refracting systems (details), final paragraph: object and image distances must refer to the principal planes.