Here is a complete list of where to find all the archive entries in the game. For the most part, 9S will be the one collecting most of these in Route B by hacking locked chests. A few others are unlocked in Route C while playing as A2 as well, while some will come from completing sidequests.
The one tip I can give for tracking down treasure chests is to buy the ever-useful Item Scan plugin chip from the Resistance Camp Supply Trader at the beginning of Route B. This should mark the locations of any unopened treasure chests on your minimap. Achieve 80% completion percentage to unlock the Information Master trophy.
Pearl Harbor Descent Records
(01.) YoRHa: Gunner 16 - Route C. As A2, talk to Anemone twice before leaving to deliver the philosophy book to Pascal. She then point you to a data terminal nearby.
(02.) YoRHa: Scanner 21 - Route C. As A2, talk to Anemone twice before leaving to deliver the philosophy book to Pascal. She then point you to a data terminal nearby.
(03.) YoRHa: Attacker 4 - Route C. As A2, talk to Anemone twice before leaving to deliver the philosophy book to Pascal. She then point you to a data terminal nearby.
(04.) YoRHa: Attacker 2 - Route C. As A2, talk to Anemone twice before leaving to deliver the philosophy book to Pascal. She then point you to a data terminal nearby.
(05.) Resistance: Rose - Route C. As A2, talk to Anemone twice before leaving to deliver the philosophy book to Pascal. She then point you to a data terminal nearby.
(06.) Resistance: Anemone - Route C. As A2, talk to Anemone twice before leaving to deliver the philosophy book to Pascal. She then point you to a data terminal nearby.
(07.) Pearl Harbor Descent Summary - Route C. As A2, talk to Anemone twice before leaving to deliver the philosophy book to Pascal. She then point you to a data terminal nearby.
(08.) Letter to the Forest King - Complete the sidequest: Treasure Hunt at the Castle.
(09.) 11B's Escape Plan - Obtained during the sidequest: 11B's Memento.
(10.) Jackass's Bomb Recipe - Complete the sidequest: Sorting Trouble 3.
Server Machine Records
(01.) Library Index - Route C. Found when A2 visits the library in the Tower.
(02.) Human Server Records - Route C. Found when A2 visits the library in the Tower.
(03.) Tower System Outline - Route C. In a locked chest within the Soul Box (Flooded City) Recovery Unit.
(04.) Class 1 Patient Health Record - Route C. Found when A2 visits the library in the Tower.
(05.) [Top Secret] Black Box - Route C. In a locked chest within the Soul Box (Flooded City) Recovery Unit.
(06.) [Top Secret] Model No.2 - Route C. Found when A2 visits the library in the Tower.
(07.) [Top Secret] YoRHa Disposal - Route C. Given by the machines when playing as 9S in the Tower.
(08.) Weapon Shop Flyer - Locked chest in the same location as the Phoenix Dagger weapon during the sidequest Lord of the Valley.
Engel's Memories
(01.) Engels 110-B Record 0005 - Complete the sidequest: Machine Examination 1.
(02.) Engels 110-B Record 0010 - Complete the sidequest: Machine Examination 2.
(03.) Engels 110-B Record 0020 - Complete the sidequest: Machine Examination 2.
(04.) Infant Machine's Memories - Automatically obtained after a story sequence in Route C.
Data Saved on Server
(01.) Shipping Records - Route B. Found in the Bunker's server while 9S is receiving a full-data overhaul after the events in the Copied City.
(02.) YoRHa Body Storage Records - Route B. Found in the Bunker's server while 9S is receiving a full-data overhaul after the events in the Copied City.
(03.) Council. YoRHa Records - Route B. Found in the Bunker's server while 9S is receiving a full-data overhaul after the events in the Copied City.
(04.) A Pious Robot's Will - This locked chest appears at near the underground elevator in the Abandoned Factory that the priest leads you to. Return here as 9S in Route C.
(05.) Records of Bestial Machine - Complete the sidequest: Turf War
(06.) [Top Secret] Project YoRHa - Route B. Received from the Commander after rescuing 2B in the Abandoned Factory.
Old World Information
(01.) Abandoned Factory Memo - Route C. Locked chest in the same room as the Engine Blade weapon.
(02.) Factory Cafeteria Sign - Route C. Inside a locked chest in the Abandoned Factory.
(03.) Newspaper Scrap - Route B/C. Flooded City, in a small room on the same building where you picked up the Type-3 Lance weapon.
(04.) Filthy Lottery Ticket - Route B. In locked chest on the grass under the stairs leading to the roller coaster.
(05.) Tattered Pamphlet - Route B. In locked chest at the Amusement Park Attraction Square.
(06.) Rotten Info Sheet - Route B. In locked chest by the wall to the left of the entrance to Forest Castle.
(07.) Strange Doll - Route B. Found in locked chest at the Forest Zone.
(08.) Bulletin Record - Route B. In locked chest near the Desert Housing Complex access point.
(09.) Paper Attached to Vehicle - Route B. City Ruins, in locked next to the truck by the collapsed bridge leading to the Abandoned Factory.
(10.) Ragged DVD - Route B. City Ruins, on the rooftop of one of the buildings. Reachable by performing an acrobatic long jump. (Double jump then hold X to hover, press Square to spin then dash forward)
(11.) Department Store Flyer - Route B. City Ruins, in locked chest to the right of the entrance to the commercial facility.
(12.) Nuclear Arms Manual - Route B. City Ruins, in locked chest inside one of the buildings. Only available when the Data On the Old World sidequest is active.
(13.) Mysterious Lithograph 1 - Route B. In a locked chest at the Desert Housing Complex.
(14.) Mysterious Lithograph 2 - Found with the pod scanner during the Heritage of the Past sidequest.
(15.) Mysterious Lithograph 3 - Route B. In a locked at the oasis area of the Desert Zone.
(16.) Mysterious Lithograph 4 - Route B. City Ruins, in locked chest at the underground portion of the Desert area. Directly across from a Lunar Tear flower.
(17.) Project Gestalt Report 1 - Route B. Found by taking side paths in the hacking space while opening doors for 2B at the Abandoned Factory.
(18.) Project Gestalt Report 2 - Route B. Found by taking side paths in the hacking space while opening doors for 2B at the Abandoned Factory.
(19.) Project Gestalt Report 3 - Route B. Found by taking side paths in the hacking space while opening doors for 2B at the Abandoned Factory.
(20.) Project Gestalt Report 4 - Route B. In a locked chest inside the secret cave that leads to Emil's home.
(21.) Project Gestalt Report 5 - Route C. Abandoned Factory. From the Factory: Furnace access point, move backward until you reach a room that has multiple exits. Hack one of the doors to open it and get on top of the press machine in the next room. You'll find the locked chest at the end to the right.
(22.) Project Gestalt Report 6 - Route B. City Ruins, in locked chest at the underground portion of the Desert area.
(23.) Project Gestalt Report 7 - Route B. In a locked chest inside the secret cave that leads to Emil's home.
(24.) Project Gestalt Report 8 - Route B. In a locked chest at the Desert Zone. Near the Desert Housing Complex entrance.
(25.) Project Gestalt Report 9 - Route C. Locked chest in The Tower, at the area where 9S first spots the infected YoRHa units.
(26.) Project Gestalt Report 10 - Route B. In locked chest on the Lunar Tear field at the basement of the commercial facility.
(27.) Project Gestalt Report 11 - Route C. In a locked chest in the corner of The Tower after 9S gets a new arm.
(28.) Machine Research Report - Automatically given after completing Route C.