The phrase "a firm control of" is correct and usable in written English.
It can be used when discussing the ability to manage or oversee something effectively.
Example: "The manager demonstrated a firm control of the project, ensuring that all deadlines were met."
Alternatives: "a strong grasp of" or "a solid command of".
By streamlining and having a relentless focus on ease of use, elegance and a firm control on the lines of production, Jobs absorbed the lesson of so many successful models: less is always slightly more.
Mackerras stayed in the post until 1977, exercised a firm control on the style and content of productions and was instrumental in broadening the repertory.
The higher compliance in study 1 was due to a firmer control of non-responders who were contacted with a re-explanation of the procedure early in the course.
According to Jane McGonigal, Ph.D. and author of SuperBetter: A Revolutionary Approach to Getting Stronger, Happier, Braver and More Resilient -- Powered by the Science of Games, getting a firmer control on your powers of attention is a crucial first step to improving your productivity.
The government said last month it was investigating some current and former public officials for their role in a proposed carbon deal that would have given a British firm control of a fifth of the country's rainforests.
He was killed in a shootout during a raid on a building in the Adhamiya district, an area under the firm control of Iraqi forces and one of the Sunni citizen patrol groups known as the Awakening Councils.
On Wednesday, he campaigned for candidates on his slate by appearing at a rally at a soccer stadium in Najaf, a province currently under the firm control of the Islamic Supreme Council of Iraq, another main Shiite party that is running separately in the elections.
It would also give allied forces firm control of a "Scud Box," or a region north of Basra that the Iraqis have used to launch surface-to-surface missiles at American forces and other targets in Kuwait.
By nightfall, government forces seemed to have firm control of a small town and factory about a half mile east of Bin Jawwad.
