For public domain text not available online, you could use academic referencing style e.g Harvard style "Jess (2021) My Public licence poems"
Loko ndzimana yo voniwa hi mani na mani yi nga ri kona eka Internet, u nga tirhisa endlelo ra dyondzo ro kombetela, hi xikombiso, endlelo ra Harvard  "Jess (2021) My Public licence poems"