Wasteland Historian

Wasteland Historian is an achievement which requires that 45 lore items are found and viewed in a single playthrough. There are more than 45 pieces of lore that count toward this achievement, but some are mutually exclusive or only available if certain decisions are made. 45 lore items should be obtainable regardless of the choices the player makes, as long as the ones available in Arizona are gathered before moving on to California.

See also: Lore Entries page at Wasteland Wiki (Wikia)

Note that some item locations have changed since Beta and as a result some information may be unreliable.

Arizona
If both the Ag Center and Highpool are destroyed, only 33 lore items may be found before leaving Arizona. Most players aiming for the achievement should be able to gather 35.
 * Intelligence report (2 parts)
 * Memories of My Time in the Rangers (3 parts)
 * The History of the Desert Rangers (6 parts)
 * History of the Ag Center (4 parts)
 * The Story of John Henry (3 parts)
 * Farmer's diary (5 parts)
 * The Servants of Titan (3 parts)
 * Anger Management for Angry Managers
 * Your Friend The Great Glow
 * The History of the Davis-Monthan Air Force Base
 * KPOW playlist for Monday July 21st
 * Double Six tragedy report
 * Blood-stained journal
 * The Flame Deluge Canticle

Route exclusive
If the Ag Center is saved first: If Highpool is saved first:
 * Garden journal
 * Lab journal
 * The Legend of the Red Ryder
 * The Ballad of Bobby & Rex

California
Players who were thorough in Arizona should only need to gather 10 more in LA to obtain the achievement. However, 12 are available.
 * The Story of Samson (4 parts)
 * Mr. Manners' Guide to Post-Apocalyptic Etiquette
 * The Ten Commandments of James King
 * Welcome to Hollywood!
 * Stolls' Journal
 * The Griffith Observatory: A History
 * Blood-stained journal (Donald)
 * Your Golden Future
 * The Gospel According to Matthias

Unavailable in-game or location unknown

 * A Brief History of the Watts Towers
 * Welcome to the Los Angeles Memorial Coliseum