Friedmann's 1922 manuscript
Friedmann_1922_b1
Friedmann_1922_b2
Friedmann_1922_b3
Friedmann_1922_b4
Friedmann_1922_b5
Friedmann_1922_b6
Friedmann_1922_b7
Friedmann_1922_b8
Friedmann_1922_b9
Friedmann_1922_b10
Friedmann_1922_b11
Friedmann_1922_bfigure