@misc{Cunningham_Allan_Joseph_Champneys_(1842–1928)_On_1891-1892,
 author={Cunningham, Allan Joseph Champneys (1842–1928)},
 volume={XXI},
 editor={Glaisher, James Whitbread Lee (1848–1928)},
 copyright={Public Domain},
 journal={The Messenger of Mathematics},
 address={London ;},
 address={Cambridge},
 howpublished={online},
 year={1891-1892},
 publisher={Macmillan and Co.},
 language={eng},
 language={eng},
 title={On the circle perpend-feet pencil and orthocentral axis of a complete quadrilateral},
 type={Text},
 URL={http://rcin.org.pl/impan/Content/109065/PDF/WA35_87716_cz294-1892-t21_Art31.pdf},
}