Description of build up to Sicily landing in WWII mentions the resin lamp
HyperWar: US Army in WWII: Sicily and the Surrender of Italy [Chapter 5]
Relevant bit is:-
Arriving in North Africa in April 1943, the 52d Troop Carrier Wing was considered fully qualified in dropping parachutists and towing gliders, but only on daylight missions. Accordingly, the troop carrier units concentrated on night formation and navigational flying, using both normal navigation lights and, later, as proficiency increased, small and lavender-colored resin lights, which would be the only aids available during the Sicily operation. But no real effort was made by the wing to check the location of pinpoint drop zones at night. A night joint training program with airborne troops and carriers fared poorly