he had already published a major work on control of systems contrôle optimal de systèmes gouvernés par des équations aux dérivées 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 Contrôle optimal de systèmes gouvernés par des équations aux dérivées partielles in 1968 which investigates deterministic optimisation problems involving partial differential equations.