"especially those regarding" is a correct and usable phrase in written English.
You could use it to introduce a sentence that focuses on a subset or type of something that has already been mentioned. For example, "There are a lot of rules for driving in the city. Especially those regarding speed limits must be followed at all times."
Please study the course Policies, especially those regarding collaboration on assignments.
The Zarnowitz thesis: All deficit forecasts are acutely sensitive to the economic assumptions that underpin them, especially those regarding future growth rates of GDP.
If the charges in the complaint are true, especially those regarding the specifics of the investigation, then Rodriguez could indeed credibly claim to be at least a partial victim of what the suit calls a "witch hunt" by the league.
Maps of climate zones are valuable for a wide range of studies on climate change and its impacts, especially those regarding the water cycle that is strongly regulated by the combined conditions of precipitation and temperature.
The increasing spread of photovoltaic (PV) systems occurring nowadays does not always keep pace with respective legislative initiatives, especially those regarding a specific relation between PV systems, the natural environment and landscape.
The resulting geographical, geological, and meteorological observations, especially those regarding the Central Asian regions, were of great importance to the Western world, for Central Asia was then to a large degree unknown territory.
He talked to as many elders as he could, especially those regarded by the Inupiat themselves as experts on the past.
The conclusions drawn from these data are not always coherent, especially for those regarding psychiatric diseases, such as schizophrenic psychoses for instance [16].
Blue Republican is not so much concerned with pushing a libertarian orthodoxy (which is bound to fail and always has), but with helping all people, and especially those who regard themselves as broadly Liberal, see how so many of our prevailing political assumptions are wrong.
An authoritarian streak, an unwillingness to challenge reactionaries – especially those he regards as anti-imperialists – as well as an emphasis on the state as the lever of social change rather than collective movements suggest he cannot.
For what is created here is an ever-pulsing portrait of just how impossible and essential it is to live in close quarters with those maddening creatures called human beings, especially those you regard (Heaven help you) as family.
