@Misc{ 
  gigoht10,
  author = { Gigli, Nicola and Ohta, Shin-Ichi },
  title = { First variation formula in Wasserstein spaces over compact Alexandrov spaces },
  journal = { Canad. Math. Bull. },
  year = { 2010 },
  pages = {  },
  URL = { http://cvgmt.sns.it/paper/845/ },
  note = { cvgmt preprint}
}