I couldn't think of a good digraph for the "OO" in book. The most available option is "OH", but that might mislead readers into thinking "OH" = the "o" in "over

I couldn't think of a good digraph for the "OO" in book. The most available option is "OH", but that might mislead readers into thinking "OH" = the "o" in "over" and not the "oo" in book. "Ø", then, seems like the best choice. (Also, it's the coolest looking diacritic form of "O")