Please read Alexey Sklyarenko's annotations on Pale Fire, Ada and other Nabokov works here.
Describing his perfromance in variety shows as Mascodagama (when he dances tango on his hands), Van Veen (the narrator and main character in VN’s novel Ada, 1969) says that the work of a poet, and only a poet could have adequately described a certain macabre quiver that marked his extraordinary act :
Describing the king’s escape from Zembla, Kinbote (in VN’s novel Pale Fire, 1962, Shade’s mad commentator who imagines that he is Charles the Beloved, the last self-exiled king of Zembla) mentions the good grunter (mountain farmer) in whose house the king spent the night:
Describing the king’s escape from Zembla, Kinbote (in VN’s novel Pale Fire, 1962, Shade’s mad commentator who imagines that he is Charles the Beloved, the last self-exiled king of Zembla) mentions lazy Garh, the farmer's daughter who shows to the king the shortest way to the pass:
Describing Villa Venus (Eric Veen's floramors), Van Veen (the narrator and main character in VN's novel Ada, 1969) mentions a special chair built for King Victor (the Antiterran ruler of the British Commonwealth who frequents floramors):
At the beginning of Part Five of Ada (1969) Van Veen mentions the highest forms of human thought — pure mathematics & decipherment:
In VN's novel Ada (1969) Van mishears the word gambler used by a Dutchman in the hotel with regard to his father, Demon Veen, and believes it to be 'camler:"
The action in VN's novel Ada (1969) takes place on Demonia, Earth's twin planet also known as Antiterra. In Chapter One of VN's novel Dar ("The Gift," 1937) Fyodor Godunov-Cherdyntsev mentions mir prekrasnykh demonov (a world of handsome demons) that develops side by side with us:
In Laughter in the Dark (1938), the English version of VN's novel Camera Obscura (1933), Dietrich Segelkranz (the writer, a friend of Kretschmar's youth) becomes Udo Conrad.
According to Kinbote (in VN's novel Pale Fire, 1962, Shade's mad commentator who imagines that he is Charles the Beloved, the last self-exiled king of Zembla), science tells us that the Earth would not merely fall apart, but vanish like a ghost, if Electricity were suddenly removed from the world:
Describing his escape from Zembla, Kinbote (in VN's novel Pale Fire, 1962, Shade's mad commentator who imagines that he is Charles the Beloved, the last self-exiled king of Zembla) mentions the Bera Range, a two-hundred-mile-long chain of rugged mountains: