Hamann B, Büchner C
Zentralbl Gynakol. 1976;98(23):1445-9.
The multiple physiologie stages of method by oral hormonal anticonception was reported, which have been in use in combination. Since 1969 about 362 women at the average age of 27,5 years received 10281 cycles, that means in an average cycles from 28,4 days, the stage method from 11/10 days or 7-7-7 days rhythmus.