he had already published a major work on control of systems controle optimal de systemes gouvernes par des equations aux derivees partielles in 1968 which investigates deterministic optimisation problems involving partial differential equations.

Write the above sentence using proper case.
He had already published a major work on control of systems Controle optimal de systemes gouvernes par des equations aux derivees partielles in 1968 which investigates deterministic optimisation problems involving partial differential equations.