where G is the universal gravitational constant, h is Planck's constant, and c is the speed of light. If h-bar is used instead of plain h, the corresponding time is
Planck Area, Planck Length, Planck Mass
Halliday, D.; Resnick, R.; and Walker, J. Fundamentals of Physics, 5th ed. New York: Wiley, 1996.
Shu, F. H. The Physical Universe: An Introduction to Astronomy. Mill Valley, CA: University Science Books, p. 397, 1982.
Planck Area, Planck Length, Planck Mass
