This light bulb has a G energy rating. On this light bulb you'll find a G24q-3 socket.
From OnBuy
Osram 999043835046 26 Watt Compact Fluorescent Light Dulux Lamp
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Osram 26W Dulux CFL DE 4 PIN Warm White - OS327235
Big on Electricals
Osram 26W Dulux CFL DE 4 PIN Warm White - OS327235