It is a poetry book. A nonsense song is a type of song written in fun using nonsense syllables at least in the chorus. Such a song generally has a simple melody and a quick (or fairly quick) tempo. The roots of this song type can be traced as far back as 'Shoo, Fly, Don't Bother Me' and 'Jimmy Crack Corn' to the 1890s 'Ta-ra-ra Boom-de-ay'. This last was a kind of can-can with an obvious accent on the 'boom'. Mostly it was a way of letting off steam.