'class SmoothThermistor' has no member named 'readCelsius'

[Marco-rc]

Hello,
After installing the libraries for the Heater sketch, I get the following error:

curTemp = sthermistor->readCelsius();
^~~~~~~~~~~
Multiple libraries were found for "SmoothThermistor.h"
Used: C:\Users\Marco\MARCO\ARDUINO\CONTROL_TEMP\3D_Printer_Filament_Joiner\libraries\SmoothThermistor
Not used: C:\Users\Marco\MARCO\ARDUINO\CONTROL_TEMP\3D_Printer_Filament_Joiner\libraries\NTC_Thermistor
exit status 1

Compilation error: 'class SmoothThermistor' has no member named 'readCelsius'

Could you please help me find the cause? Am I using a different version of the libraries?
This is what I have:
#include <SmoothThermistor.h>
#include <NTC_Thermistor.h>
#include <PID_v1.h>