Whether the Squatter and the Owner must be in the same region: Ketuvot 17b
Owner's Assertion of Ownership, outside of the presence of the Squatter: Ketuvot 17b
Squatter's Rights on a Minor's Property: Ketuvot 17b, Bava Metzia 39a-b
Squatter's Rights where the Minor reached adulthood after the original settlement, and then the squatter remained there for 3 years afterward: Bava Metzia 39a-b
"What-If"s
Where the owner died during those 3 years, passing it to his son: Ketuvot 17b
Where the owner left town after 2 years, due to financial danger: Ketuvot 17b
Where the owner left town after 2 years, due to physical danger: Ketuvot 17b