When Siegfried tries to open the window in the upper room that he intends for James and Helen, he refers to "Magic casements opening on to the foam". He is quoting John Keats' poem Ode to a Nightingale.
Siegfried Farnon sings part of the nursery rhyme "Mrs Bond (Dilly Dilly)", dating to the early 1800's and referenced in Charles Dicken's book David Copperfield, in the late 1840s.