Plug & Play 16 Inch T9 Circline LED Bulb Ballast Required!
Vintage circline Fluorescent Light fixture | i love these | DieselDucy | Flickr
1980's General Electric Preheat Circline T9 Lamp (Bad video quality, don't know why) - YouTube
Amatron ETL & Energy Star LED T9 Circline Retrofit Kits | AmatronLED
NYLL - 8 Inch/ 8" Plug & play Circline LED - Daylight (6000K) Circline – HomeLoft - New Zealand
GE Cool White 32 W Fluorescent 12-in Circline 4-Pin T9 Light Bulb (1-Pack) 93118034 | RONA
T9 LED Circline Light Bulb, 12 Inch 2700LM LED Circular Ceiling Light, 22W Clear Cover 6000K Daylight Replacement for 32W Circular Fluorescent Light Bulb(FC12T9), Ballast Bypass Required - - Amazon.com
CIRC Circline fluorescent
Feit Electric Color select 22-Watt EQ 8-in Cool White G24d-2 Pin Base Circline Type A LED Tube Light Bulb in the LED Tube Light Bulbs department at Lowes.com
Lighting Supply Blog: A Little Light Reading - LIGHTING SUPPLY
Satco 32W 12 In. Cool White T9 Circline 4-Pin Fluorescent Tube Light Bulb - Taylor's Do it Center