"outer side" is correct and usable in written English.
You can use it to refer to the outer surface of an object. For example: "The outer side of the box was covered in dust."
The outer side of the quires is flesh side.
Lateral collateral ligament (LCL) — The LCL supports the outer side of the knee.
"I was driving on the outer side of the ring road.
You can also rig up shutters, using sound-deadening board on the outer side.
On the outer side is the radial notch, which articulates with the head of the radius.
Growth appears to be always faster if Cu is stacked to the outer side of Al.
Therefore, a planet pulls a little bit more on the inner side of its moons than on the outer side.
You face a black screen and press your hands on sensor pads on the outer side of the machine.
(f) PCR analysis of the injected F344 rats using primers designed against each outer side of the two LTR sequences.
b Outer side, magnification ratio ×250.
a The outer side, magnification ratio ×25.
