great idea and crossovers, good mix of subjects- unfortunately you could put 2 of your musical groups into the symbol group in place of He (Re- Rhenium and Ho- Holmium)- Red herrings need to only work one way or there is no one unique solution. I love this grid as a concept, works really well :)

Broad subject matter but I guess with the books group you either know ‘em or you don’t!