Recruitment and retention of urban schoolchildren into a randomized double-blind vitamin D supplementation trial
Titel:
Recruitment and retention of urban schoolchildren into a randomized double-blind vitamin D supplementation trial
Auteur:
Sacheck, Jennifer M Van Rompay, Maria I Olson, Elizabeth M Chomitz, Virginia R Goodman, Elizabeth Gordon, Catherine M Eliasziw, Misha Holick, Michael F Economos, Christina D