WE HAVE A SOLUTION TO THIS, THEY ARE CALLED FOOTNOTES.
"COME OUT COME OUT AND FLIP TO THE BACK OF THE FUCKING BOOK AND SEARCH FOR THE TINY NUMBER. OH YOU HAVE A PDF? THEN FUCK YOU AND YOUR FUCKING LIFE" - DERANGED SICKO PUBLISHERS
Under communism, endnotes will be banned and punishable by law.
I can't remember which book it is but this is definitely an early PTerry bit.