Pretty_little_liars_3x06

In the Pretty Little Liars episode "The Remains of the 'A'" (Season 3, Episode 06), the "interesting paper" most likely refers to the found by Hanna and Spencer .

: Spencer realizes the blueprint is dated months before the construction of that wing actually began. Pretty_little_liars_3x06

: This paper leads them to discover that a room was built into the sanitarium that wasn't on the official public records—a room that "A" (Mona) was using to sneak in and out of the facility. In the Pretty Little Liars episode "The Remains

Another notable paper trail in this episode involves the Hanna finds in Wilden’s car, which places him in a different location than he claimed during the time of the "remains" discovery. Pretty_little_liars_3x06