1. Effects of folic acid and zinc sulfate on male factor subfertility: a double-blind, randomized, placebo-controlled trial 
Wai Yee Wong, M.D, Ph.D., Hans M.W.M Merkus, M.D., Ph.D., Chris M.G Thomas, Ph.D., Roelof Menkveld, Ph.D., Gerhard A Zielhuis, Ph.D., Régine P.M Steegers-Theunissen, M.D., Ph.D. 
Fertility and Sterility 
Volume 77, Issue 3, Pages (March 2002)
DOI: /S (01)

2. Figure 1
Trial profile.
Wong. Folate, zinc, and male subfertility. Fertil Steril 2002.
Fertility and Sterility  , DOI: ( /S (01) )

3. Figure 2
Median preintervention and postintervention sperm concentrations in subfertile (A) and fertile (B) men. ∗P<.001 for comparison between baseline and posttreatment values. ■ pre-intervention; □ postintervention.
Wong. Folate, zinc, and male subfertility. Fertil Steril 2002.
Fertility and Sterility  , DOI: ( /S (01) )