The basic physical principles common to all nonresonant and resonant thermonuclear reaction rates are taken as a basis to derive the standard forms of both types of reaction rates. Results are given for the closed-form representations of the standard nonresonant and resonant thermonuclear reaction rates in terms of a certain type of Meijer's G-function. Then, for physical reasons the nonresonant reaction rate with modified Maxwell-Boltzmann distribution is considered. The mathematical method for the derivation of closed-form representations for the modified nonresonant reaction-rate integral, which is also suitable for numerical computations, is given in detail. Some new techniques developed by the authors are used for deriving the results. The reaction-rate systematics thus obtained in terms of Meijer's G-function is a contribution to Fowler's methods for the numerical computation of thermonuclear reaction rates. © 2015 Wiley Periodicals, Inc., A Wiley Company.