In "Hitagi Rendezvous", Araragi speaks to Ononoki after Senjougahara proposes a date for the next day. Ononoki is shown reading something while lying on Araragi's bed.
Do we know what she is reading? Does it correspond to any work that exists in real life? I tried Googling アガジソ, which I believe to be the correct order of the katakana on the cover and spine, but there weren't any results that made sense to me. (It makes more sense for the katakana on the cover to be read right to left than for the identical string of katakana on the spine to be read bottom to top.)