@article{PPN588764140+DMDLOG_0021, title = {Paper XXI. On the Focal Properties of Homographic Figures.}, booktitle = {The collected mathematical papers of Henry John Stephen Smith Vol. 1}, series = {GDML\_Books}, publisher = {Clarendon Press}, address = {Oxford}, year = {1894}, pages = {545}, url = {http://dml.mathdoc.fr/item/PPN588764140+DMDLOG_0021} }
(éd.). Paper XXI. On the Focal Properties of Homographic Figures., dans The collected mathematical papers of Henry John Stephen Smith Vol. 1, GDML_Books, (1894), p. 545. http://gdmltest.u-ga.fr/item/PPN588764140+DMDLOG_0021/