1. Effect of 21-day and 24-day oral contraceptive regimens containing gestodene (60 μg) and ethinyl estradiol (15 μg) on ovarian activity 
Helen Sullivan, M.D., Hilary Furniss, Jurgen Spona, Ph.D., Max Elstein, M.D. 
Fertility and Sterility 
Volume 72, Issue 1, Pages (July 1999)
DOI: /S (99)

2. FIGURE 1
Mean diameter of largest follicle-like structure with 21- and 24-day regimens. ■, 7-day pill-free interval; ■, 4-day placebo-pill interval; --○--, 24-day; –■–, 21-day.
Fertility and Sterility  , DOI: ( /S (99) )

3. FIGURE 2
Mean serum 17-β-E2 concentration with 21- and 24-day regimens. ■, 7-day pill-free interval; ■, 4-day placebo-pill interval; --○--, 24-day; –■–, 21-day.
Fertility and Sterility  , DOI: ( /S (99) )