The phrase "a still unknown" is not correct in standard written English.
It can be used when referring to something that remains unidentified or not yet discovered, but it should be rephrased for clarity.
Example: "The cause of the phenomenon is still unknown to researchers."
Alternatives: "still unidentified" or "yet to be discovered."
Most of the mass of the universe is believed to be in "dark matter," a still unknown form of matter.
Emergence behaviour is modulated by the day night cycle but a further modulation occurs upon social interaction in a still unknown fashion.
The acquisition, she remembers, felt more than a commodity exchange; in a still unknown city, she says, "it felt like purchasing citizenship".
But just as the final compromise was about to pass, the 12-year campaign was snuffed out by a still unknown senator exercising an anonymous hold.
There are obvious problems: which 90% do you aim at, for instance, and what is 90% of a still unknown total, anyway?
Alexandra Missagia, 47, said she had been working all day prepping her home for the storm, and wanted one night out before she was cooped up during a storm with a still unknown impact on Miami.
However, he learned to do the Marāgheh "trick," either independently or through a still-unknown intermediary link.
The findings also indicate that ALS comes in at least two forms — one in which RNA-binding function is disrupted, and the other with a still-unknown mechanism.
A man identified as a former employee entered the hotel wearing a surgical mask and sprayed a still-unknown liquid all over the lobby.
The car bombs prepared for use in both attacks were virtually identical, with a magnetic outer shell that was smuggled into the two countries, to be combined later with C4 military explosives obtained from a still-unknown source.
10.04am: The UN secretary-general, Ban Ki-moon, has made an emotional visit to his organisation's collapsed headquarters in Port-au-Prince, where a still-unknown number of UN staff were killed.
