Why, when Harry used Expelliarmus on Snape in Prisoner of Azkaban, did it blast him backwards and not disarm him as the spell is supposed to do? - Quora
Why did Snape's Expelliarmus knock Lockhart off his feet when normally it just knocks the weapon from the hands? - Quora
The Harry Potter books from Severus Snape's Perspective | Pottermore on Quotev
Hogwarts Legacy Expelliarmus Severus Snape at Hogwarts Legacy Nexus - Mods and community
Professor Snape - Television and Film Character Encyclopedia