What calendar is primary used to organize historical time

How was rockefeller able to build his monopoly across the oil industry? he found newer and cheaper ways to refine oil, increasing his profits. he confined his business to ohio so he could buy all the refineries there. he bought up oil refineries, cut costs, and reinvested his profits in other refineries. he began to sell kerosene as well as oil, expanding his market.

What treatments did king henry the 8th get after the horse accident?

Jacksonian democracy promoted new methods of political campaigning. one such technique was mudslinging. what was its effect on the presidential candidates?