The phrase 'principal methods' is correct and can be used in written English.
It is typically used to refer to the main ways of doing something. For example, "The principal methods of achieving a successful outcome were to remain focused and to stay organized."
Oxidation is among the principal methods.
There are two principal methods of preparing nitrides.
There are three principal methods, differing by their means of supplying heat.
Only a broad outline of the principal methods can be given here.
Anhydrous magnesium chloride is produced by two principal methods: dehydration of magnesium chloride brines or chlorination of magnesium oxide.
There are four principal methods of chartering a tramp ship voyage charter, time charter, bareboat charter, and "lump-sum" contract.
While the basic tala is always in a performer's consciousness, one of the principal methods of creating excitement in a performance is to play rhythmic patterns that contradict the tala but eventually return to its fundamental scheme.
One of the principal methods of forecasting the financial needs of a business is the cash budget, which predicts the combined effects of planned operations on the firm's cash flow.
August 24, 1898 Longlier, Belgium May 22 , 1983Brussels, Belgium Albert Claude, (born August 24, 1898, Longlier, Belgium died May 22 , 1983 Brussels) Belgian-American cytologist who developed the principal methods of separating and analyzing components of the living cell.
The national budget generally reflects the economic policy of a government, and it is partly through the budget that the government exercises its three principal methods of establishing control: the allocative function, the stabilization function, and the distributive function.
Currently there exist two principal methods for measuring blood pressure: the sphygmomanometer and the catheter.
