"refers solely" is correct and can be used in written English.
You can use it when you're describing something that only applies to a single entity or subject. For example, "This policy refers solely to employees under the supervisor's direct supervision."
It should be noted that the recorded AZFc mutation rate represents a conservative estimate since it refers solely to changes in the number or order of the reference sequence amplicons.
The word afghani refers solely to the country's main unit of currency.
Re "The claim: Sex before an athletic event can hinder performance" ("Really?," Aug. 31): The study refers solely to the experiences of men.
The Sept. 24 deadline refers solely to hydrocarbon-bearing zones in the Chukchi, not upper, shallow sections of a well, the company says.
The most interesting thing about the term "auteur" is that though it's the ordinary French word for "author," in English, it refers solely to movie directors, especially those whose work is deemed artistically ambitious.
A second possibility is to distinguish first-order from second-order attributions, where "ineffability" both is a second-order term and refers solely to first-order terms.
In what follows, for simplicity we refer solely to 'the rate' of crime per 100,000 persons without reference to it being based on police recorded crime data.
Its $20.5 billion figure referred solely to corporate information technology globally.
Later, spokespeople from the State Department and the D.H.S. said that this referred solely to Jamaican officers.
Some would prefer this to be interpreted narrowly, as referring solely to the short-term financial interests of the shareholders.
When, in "Dancing Crazy," Cosgrove sings about "going all night" or "hot hot," she's referring solely to the dance floor.
