(en) Baynes, Thomas S.; William Robertson Smith, Angaria (Wikisource). Encyclopædia Britannica - Ninth Edition, Volume 2 (1880). Gearchiveerd op 3 september 2023.
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(en) Baynes, Thomas S.; William Robertson Smith, Angaria (Wikisource). Encyclopædia Britannica - Ninth Edition, Volume 2 (1880). Gearchiveerd op 3 september 2023.