"The Perfect Gaming Zone" has a video guide detailing how to find all of these collectables:
From their description, the summary of collectables is as follows:
*** Spoiler - click to reveal ***
RESEARCH & RECORDS
Hiss Research
- AUTO - Hiss Ranger (Airborne)
Reports
- Alice Wake Interview
- Black Market
- Blessed Organization
- Darling Investigation
- Director Investigation
- Door Appearance
- Employee Misdemeanor
- Ethics Investigation
- Hartman Arrest
- Hartman Background
- NASA Cooperation Review
- Shaded Specimen Captured
- Specimen Escape Assessment
- Underhill Background
- Wake Evidence
Research
- Night Springs Screenplay Pg. 1
- Night Springs Screenplay Pg. 2
- Night Springs Screenplay Pg. 3
- Night Springs Screenplay Pg. 4
- Shaded Hartman
- The Shadow
- Wake Photograph
CASE FILES
Altered World Events
- Bright Falls (1976) Summary
- Bright Falls (1976) Supplement
- Eagle Limited Summary
- Eagle Limited Supplement
- Fra Mauro Summary
- Fra Mauro Supplement
Altered Items
- Arcade Cabinets Procedures
- AUTO - Arcade Cabinets Supplement
- Tractor Procedures
- Tractor Supplement
- AUTO - Train Car Procedures
- Vending Machine Procedures
CORRESPONDENCE
Official
- Casey Inquiry
- Cauldron Lake Update
- Missing Agents
- Resignation Letter
- Trench: Official Warning
Non-Official
- AUTO - Ahti Postcard
- Chain Letter
- Interrogation Complaint
- Keystone Inspection
- Motel Complaint
- Staffing Issue
Dead Letters
- Actor for Hire
- Brain Missing
- Foot Gossip
MULTIMEDIA
Interviews
- Brian Hennerman Interrogation
- Dr. Hartman Interrogation
- Fra Interrogation
- Langston Interrogation
- Suspect Interrogation
FBC Recordings
- Dr. Hartman's Notes: Next Steps
- Dr. Hartman's Notes: The Darkness
- FBC Reminder: Billable Hours
- FBC Reminder: Law of Three
- Motel Observation
Music
- Langston: Freestyle
- Langston: Me and You