[1] T. A. Cook:
The Nikodym-Hahn-Vitale-Saks theorem for states on a quantum logic. Math. foundations of quantum theory (Proc. Conf., Loyola Univ., New Orleans, 1977) p. 275-286.
MR 0503098
[2] A. Dvurečenskij:
Signed states on a logic. Math. slovaca, 28 (1978), 33-40.
MR 0527772
[3] A. Dvurečenskij:
On convergences of signed states. Math. slovaca 28 (1978), 289-295.
MR 0534996
[4] A. M. Gleason:
Мeasures on the closed subspaces of a Hilbert space. J. Math. Mech. 6 (1957), 885-893.
MR 0096113