31 cards where the illustration contains “bookmark”

Arcane Encyclopedia (Commander Legends: Battle for Baldur's Gate #297)
Arcane Encyclopedia (Core Set 2019 #227)
Arcane Endeavor (Forgotten Realms Commander #14)
Archivist (Urza's Legacy #26)
Artificer's Assistant (Dominaria #44)
Barrin's Codex (Urza's Saga #286)
Book of Rass (The Dark #98)
Browse (Alliances #25)
Dark Tutelage (Magic 2011 #90)
Demonic Lore (Commander Legends #118)
Eager First-Year (Strixhaven: School of Mages #16)
Emmessi Tome (Eternal Masters #221)
Enthusiastic Study (Strixhaven: School of Mages #99)
Ertai's Familiar (Weatherlight #38)
Flash of Insight (Judgment #40)
Fool's Tome (Tempest #289)
Gadwick's First Duel (Wilds of Eldraine #51)
Island (Jumpstart #53)
Jayemdae Tome (Limited Edition Alpha #254)
Jodah's Codex (Dominaria United #233)
Mild-Mannered Librarian (Jumpstart 2022 #41)
Mystic Redaction (Modern Horizons 2 #53)
Mystic Redaction (Modern Horizons 2 #338)
Necrosavant (Multiverse Gift Box #4)
Novellamental (Unstable #41a)
Otherworld Atlas (Avacyn Restored #219)
Rescue (Dominaria #63)
Tome Scour (Magic 2010 #76)
Urza's Tome (Dominaria #235)
Venser's Journal (Scars of Mirrodin #220)
Wild Research (Apocalypse #72)

The message was clear to Sorin—time to search for something else.