In an article that announces the publication of his Russian version of Ada Mr. Babikov affirms that, as a young man, VN made an inscription on his copy of “Madame Bovary:” Livre génial — la perle de la littérature française:
Сам же он отводил «Аде» точно определенное место в мировой литературе, написав на форзаце своего экземпляра: «Гениальная книга — перл американской литературы», как в молодости сделал надпись на экземпляре «Госпожи Бовари»: "Livre génial — la perle de la littérature française".
Actually, it was VN’s father, Vladimir Dmitrievich Nabokov (a great admirer of Flaubert), who inscribed the book before giving it to his son.
The news about the forthcoming appearance of Mr. Babikov’s version (judging by the above example, which looks like a mistranslation from Boyd's book, one can easily imagine how many blunders it contains) makes me start publishing without delay my own faithful and poetic translation of Ada (perhaps, even on this site). So I may leave the Forum for a time being (I hope, not for good).
As pointed out by Stas Shvabrin (in an email to me), in Speak, Memory (Chapter Nine, 1) VN writes:
Thirty years later, a fellow student of his, with whom he had gone for a bicycle trip in the Black Forest, sent my widowed mother the Madame Bovary volume which my father had had with him at the time and on the flyleaf of which he had written “The unsurpassed pearl of French literature” — a judgment that still holds.
So VDN gave an inscribed copy of Flaubert's novel to a friend, not to his son.
VN wrote on the flyleaf of his copy of Ada: гениальная книга - перл американской словесности (brilliant book - a pearl of American literature).