"side on which" is correct and usable in written English.
It can be used to refer to a specific side or face in relation to something or someone else. For example: "Be sure to stand on the side on which the wind is not blowing".
It was folded in half so we could see only one side, on which she'd written the number of cells of each of our eight embryos.
The issue, in his view, was the broader slide into mob rule happening throughout America, and he wrote, "When the question lies between justice regularly administered or the wild vengeance of a mob then there is but one side on which the patriot and Christian can rally".
The side on which the victim is the one who has to cover his tracks.
The patient's task was to indicate the side on which the colored squared was, and the examiner pressed one of two buttons of the response box (CT3; Cambridge Research Instruments, Cambridge, UK) that corresponded to the position of the square.
No one could ever accuse Cristiano Ronaldo of ignorance as to the correct side on which to apply (fat-free) butter to (carb-free) bread; not only did he omit Lionel Messi from his voting paper for the Ballon d'Or, but Franck Ribéry too.
This is an embarrassing oversight, especially for the atheist side (on which my sympathies generally lie).
It is also the side on which most composers of musicals and film scores began their careers.
I clamber over some hillocks so that I see the reverse of a yellow trail sign, the side on which there's no writing.
"Men get to enjoy the technical aspect of having two sides on which to display complications.
In fact, both men have argued that the world can do both, but they represent opposite sides on which priority to value more highly.
The samples were irradiated with a full range of X-radiation (W-anode, 50 kV, 10 mA), on both sides, on which aluminum contacts were coated.
