Journal

A journal is a type of written document, they take the form of either personal accounts, akin to a diary, or professional publications, similar to magazines.

Personal journals
Some Klingons were known to keep journals. Kahlor, son of Kolox maintained a journal while serving under Kor, son of Rynar on the campaign to take Organia. These records were later kept in the chronicles of the House of Kahnrah and were studied by Kahnrah in 2293 when he was studying the history of Klingon-Federation relations to help inform his decision on whether or not to support Chancellor Gorkon's proposal to open peace talks with the Federation. 

Professional journals

 * Kropasar Journal of Applied Biotechnology
 * Journal of Applied Warp Mechanics
 * Journal of Archaeological Studies
 * Journal of Experimental Psychology
 * Journal of Quantum Medicine
 * Starfleet Medical Journal