Japanese Type 89 Mortar Rounds

[Bobby]

Hello. Is there a good reference source, either on line or in print, that discusses the varieties of Japanese type 89 mortar rounds? And what to look for when buying an inert round? I have been checking for a reference without success so far. I sometimes come across them at shows and auctions and would like to learn more about them. Picture of one shown below. Thank you.

[Ryoyo]

As for what to look for, collectors love it when these have good original paint and markings, and of course, overall condition and completeness of parts.
Reference of the different types of rounds is a bit slim. Most of the ones you see are HE with the yellow stripe if paints survives. Any variants are going to be much rarer.
For a basic overview, check
Japanese 50mm Knee Mortar - Inert-Ord.net

Some books
The Knee Mortars of Japan 1921-1945
Nippon no Gunyoju to Sogu (Japanese, but mostly photos)
Department of the Army Technical Manual TM 901985-5, Japanese Explosive Ordnance (Army Ammunition, Navy Ammunition (Hard to find and expensive, but there might be reprints)

[Bobby]

Wonderful information. Thank you.