The phrase "a combination of certain" is correct and usable in written English.
It can be used when describing a mix or blend of specific elements or factors.
Example: "The success of the project was due to a combination of certain strategies that were implemented effectively."
Alternatives: "a mix of specific" or "a blend of particular".
This is a combination of certain elements capable of accumulating and producing potential hydrocarbons.
Further study is necessary to understand the role of a single or a combination of certain catalysts necessary for CNT growth.
Etiquette, she says, is really a combination of certain principles (respect, honesty, consideration), while manners are "the tools we use to articulate those principles".
A promising strategy to accelerate joint implant integration and reduce recovery time and failure rates is to deliver a combination of certain growth factors to the integration site.
The leg system of the beach animals works because of a combination of certain lengths of tubes.
This low efficiency was presumably due to a combination of certain properties of the plastic ware and the shape of the tubes since better efficiencies could be achieved using a smaller volume in the same tubes.
Thus, fear might be a combination of a certain thought (the thought that there is an abyss ahead), a certain desire (a desire not to fall), and certain sensations (those peculiar to anxiety).
A combination of almost certain failure by the BBC to secure an inflation-busting licence fee settlement, the growth of independent production and technological change rendering large studios redundant, could lead to the building being sold.
In these tests, Facebook's Safety Check will be triggered by a combination of a certain number of people posting about a particular crisis plus an alert from one of Facebook's third-party sources.
The study reveals that the ear height and profile can be minimized by an optimized combination of certain texture components including their scatter width.
And Hawthorne & Uzquiano (2011) raises other cardinality problems for a combination of necessitism with certain common mereological assumptions.
