TY - JOUR AU - Daniele Ettore Otera TI - Double points and universal covers JO - Filomat PY - 2022 SP - 1171 VL - 36 IS - 4 UR - http://geodesic.mathdoc.fr/articles/10.2298/FIL2204171O/ DO - 10.2298/FIL2204171O LA - en ID - 10_2298_FIL2204171O ER -