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 .

: 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. Pretty_little_liars_3x06

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. In the Pretty Little Liars episode "The Remains

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