Does anyone recall this linear algebra survey of results?
core.ac.uk/reader/82344482
Here the result is cited. Following the reference, you find
culturagalega.gal/album/docs/textos_214_18.pdf
that is the original paper where it is proved.
I don't know if one of those is the paper you were looking for, but you can for example look for papers citing one of those and then go down the white rabbit's hole.
Found the book, its Problems and Theorems in Linear Algebra, by V. Prasolov.