I have searched for this in the past and I haven't seen any official professional statement, which by the way, is a pity. I have seen people submit personal let

I have searched for this in the past and I haven't seen any official professional statement, which by the way, is a pity. I have seen people submit personal letters from prestigious professors stating it instead. In my view, the CS community is somewhat US-centric in this respect... it's not a huge problem for US professors (many of them publish exclusively or almost exclusively in conferences and they seem to be fine) so not much is done, unfortunately.