Levinson N
Department of Mathematics, Room 2-365, Massachusetts Institute of Technology, Cambridge, Mass. 02139.
Proc Natl Acad Sci U S A. 1974 Apr;71(4):1013-5. doi: 10.1073/pnas.71.4.1013.
Starting from the derivative of the functional equation of the zeta-function, it is shown that at least one-third of the zeros of the zeta-function are on the line sigma = (1/2).