Paper XXI. On the Focal Properties of Homographic Figures.
The collected mathematical papers of Henry John Stephen Smith Vol. 1, GDML_Books, (1894), p. 545 / Harvested from
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@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/