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Matthew Ando. Isogenies of formal group laws and power operations in the cohomology theories . Duke Math. J., 79(2), 1995. MR 97a:55006

R. Bruner, J. P. May, J. E. McClure, and M. Steinberger. ring spectra, volume 1176 of Lecture Notes in Mathematics. Springer, 1986. MR 88e:55001

A. J. Baker and U. Würgler. Liftings of formal groups and the Artinian completion of . Math. Proc. Cambridge Phil. Soc., 106:511-530, 1989. MR 90i:55008

Jack Morava. Forms of -theory. Math. Z., 201:401-428, 1989. MR 90e:55011