Input in one cell to output to another cell and vise versa

https://preview.redd.it/3qm6ng64bzxg1.png?width=865&format=png&auto=webp&s=1be61b904592b6b2881f6c1a61f7eb4502530d24

I got this error above trying to do the following:

Is there a way to have two sheets output information back and forth depending on which sheet you put information on?

sheet1 '=sheet2!A1'

sheet2 '=sheet1!A1'

I basically I want two input sheets carry over information to a 3rd sheet but the user can pick sheet1 or sheet2 but all info would carry over in order for the reviewer to also pick which sheet to review. Hopefully that makes sense.