Beside the one tank encyclopedia shared here, what are good general sources on tanks and AFVs, such as books available on Libgen and elsewhere? I've found:
>Richard Ogorkiewicz — Tanks: 100 years of evolution
>Kenneth Macksey — Tank warfare: a history of tanks in battle
>Spencer C. Tucker — Tanks: an illustrated history of their impact
>Christopher F. Foss — Jane's tanks and combat vehicles recognition guide
>John Nicholas — Main battle tanks
>Marsh Gelbart — Tanks: main battle tanks and light tanks

Also leaving this .pdf with technical minutiae on the Osório, it's hard to find now.
Looked into what Argentina has and they were successful in a Tamoyo-like project i.e. a lightweight pseudo-MBT for a poor military, the TAM, a 30-ton Marder with a 105 mm gun. It competed against the Tamoyo in Ecuador and won.