What is the correct circuit symbol for a thermistor?

[xunxine]

I came across a few variations of the circuit symbol for thermistor. I've attached one below.
I'm more used to the version with horizontal line at bottom left and rise to the top right. Is there any fixed or correct version? Or are all equally correct? i.e. the orientation of the line doesn't matter?

 

[berkeman]

I came across a few variations of the circuit symbol for thermistor. I've attached one below.
I'm more used to the version with horizontal line at bottom left and rise to the top left. Is there any fixed or correct version? Or are all equally correct? i.e. the orientation of the line doesn't matter?

I use that symbol for MOVs (metal-oxide varistors for surge clamping). I prefer more of a resistor symbol with an arrow through it for a thermistor.

Vishay seems to use that symbol for their thermistors, though.

 

[Mike_In_Plano]

Seems like we always drew a circle around it and made a note of the resistance @ temp.

 

[xunxine]

Corrected above: I'm more used to the version with horizontal line at bottom left and rise to the top right.

For the diagram of resistor with an arrow through it, i learned it as a variable resistor or rheostat.
I didn't know there's a symbol for MOVs.