CALCULATOR CASIO FX-31 TESTED BLUE VFD DISPLAY SCIENTIFIC W/ ORIGINAL AC ADAPTER | eBay
VFD Display for the TI83+ Calculator : 12 Steps (with Pictures) - Instructables
File:Vintage Radio Shack Electronic Pocket Calculator, Cat. No. 65-638A, Model EC-495, 12 Digit Green VFD, Made in Taiwan, Circa 1978 (11972057203).jpg - Wikimedia Commons
Turn a VFD 1970s Calculator Into a Digital Clock : 20 Steps (with Pictures) - Instructables