If you are fortunate enough to have Grandma’s high school or college yearbook, it still may be to your advantage to look at digital images of that same yearbook. It could be that Grandma wrote in her friend’s yearbook and that friend’s yearbook was the one that was digitized and put online. When digital images of yearbooks are posted online, those signatures and notes of “best wishes” are usually not indexed. You will have to search for them by hand–if you are lucky enough to find a digital copy with personalized notes.