My high school calculator Casio fx - 39 from 1981 year and his friend ElsiMate : r/calculators
Original Casio Fx-991ex Advanced Scientific Calculator 552 Functions Engineering Students High School Lab Office Solar - Battery - Calculators - AliExpress
Casio fx-39 - Scientific calculator from 1978 - YouTube
Index of /Museum/Calculator/FX/FX-39
Vintage Retro 1970s Casio Scientific Calculator Fx-39 Made in Japan for sale online | eBay