For this research you need to have Research tower at level 5.
Researching these crafting manuals is used to unlock more powerful manuals that give you more refined material for the same costs.
You need to start by researching short manuals. After researching 5 manuals the long manuals will be unlocked. The same system applies also to the ruby manuals. You need 5 long manuals, then you can research ruby manuals.
Refined wood (Refinery)
Refined stone (Refinery)
Screw, black powder, saw, drill, crowbar, leather strip, chain, metal plate (Toolsmith)
Dragon scale tile
Dragon Charms, Steel, Dragon glass, Twin Flame Axes, Dragon Glass Arrows, Dragon Scale Armor, Dragon Scale Arrows
