The phrase "a stable core of" is correct and usable in written English.
It can be used to describe a fundamental or essential part of something that remains consistent or reliable.
Example: "The organization has a stable core of dedicated volunteers who ensure its success."
Alternatives: "a solid foundation of" or "a reliable base of".
But T.F.A., Ravitch concluded, is not building a stable core of good teachers.
When the telecoms group was privatised at the end of 1997, the treasury ministry thought it had assembled a stable core of shareholders.
The nucleoporins that build the NPC are arranged in a stable core of module-like subcomplexes with eight-fold rotational symmetry.
A flexible reward engine should have a stable core of rules to ensure fairness over time.
Deville and Chalhoub-Deville (2006) argue that a "focus on a stable core of abilities, which has been the usual practice in testing, affords necessary but not sufficient information about the interactional nature of contexts, and ultimately about score interpretability" (Chalhoub-Deville 2009, p. 257).
"What the students gain is a stable core of teachers and principals," said Mark Rosenbaum, chief counsel for the ACLU of Southern California, which also took part in the litigation along with the firm Morrison & Foerster.
"This was a year in which Americans tuned out headlines and proved that a stable, core group of consumers make up most of the market," Oscar Health CEO Mario Schlosser said.
Windows XP is the company's attempt to base its consumer software on a more stable core of computer code (called a kernel): the kernel used in its own Windows NT and 2000.
In the 1950s English physicist Tony Skyrme formulated field equations that predicted field patterns of "whirls" around a stable core rather like the eye of a hurricane, moving in a group like a single particle.
Furthermore, a recent report suggested TFIID can have a stable core sub-complex (consisting of TAF4, 5, 6, 9, and 12) [22].
From Felson's perspective, the group may have a relatively stable core of members who account for most of the criminal activity, but most members are peripheral and drift in and out of the group.
