• Note: For Military & Naval history, see D-F

Subclass U Military science (General)
Subclass UA Armies: Organization, distribution, military situation
Subclass UB Military administration
Subclass UC Maintenance and transportation
Subclass UD Infantry
Subclass UE Cavalry. Armor
Subclass UF Artillery
Subclass UG Military engineering. Air forces
Subclass UH Other services

Subclass V Naval science (General)
Subclass VA Navies: Organization, distribution, naval situation
Subclass VB Naval administration
Subclass VC Naval maintenance
Subclass VD Naval seamen
Subclass VE Marines
Subclass VF Naval ordnance
Subclass VG Minor services of navies
Subclass VK Navigation. Merchant marine
Subclass VM Naval architecture. Shipbuilding. Marine engineering