Google-search led me to Ellen Pifer's 2003 "Vladimir Nabokov:
Lolita, a Casebook" where she indicates Nabokov's quote from
Shelley's Ode to a Skylark. in an intriguing context.
"The Monster and the Nymphet: Frankenstein and Lolita"
(p.98)
"Betraying him at every turn, the narrator's rationalizations are as
intriguing in their self-exposure as those of his literary precursor Victor
Frankenstein. Humbert's striking kinship with the protagonist of Mary Shelley's
novel appears to have gone unnoticed - perhaps because the characters appear to
have little in common."*(19)
.................................................
*(19) Although Humbert's narrative never directly refers to Frankenstein,
Nabokov, [ ] undoubtedly read Shelley's popular classic in his
youth.[ ]Nabokov's prodigious knowlege of the English Romantics-
Byron, Wordsworth, and Percy Bysshe Shelley - as well as their European
precursors, contemporaries, and epigones is both obvious and well documented.
Nabokov, in his commentary on the translation of Eugene Onegin refers to
Shelley's "widow" when glossing a line (chap. 3 stanza 9,18) of Pushkin's novel
in verse: "According to his widow, "Nabokov comments,
"one summer evening [the poet] heard the skylark and saw the
'glow-worm golden in a dell of dew' mentioned in his famous ode"
(2.344).