I've been curious about the source of the Arcane Trickster's magic. All the player's handbook offers about the source of magic for this subclass is as follows:

PHB p. 97

Some rogues enhance their fine-honed skills of stealth and agility with magic, learning tricks of enchantment and illusion. These rogues include pickpockets and burglars, but also pranksters, mischief-makers, and a significant number of adventurers.

While this says they learn tricks and illusions, there does not seem to a lot of info on where this magic comes from and how they obtain it. I know the Arcane Trickster uses the Wizard's spell list and it seems to be backed up that in the spell casting ability section of the subclass, but while there is a focused study it's not very clear on the source of the studies.

PHB p. 98

Intelligence is your spellcasting ability for your wizard spells, since you learn your spells through dedicated study and memorization.

So, canonically where does a rogue's magic come from and how would they study to become an arcane trickster?