@misc{ wiki:xxx,
    author = "{Wikipedia contributors}",
    title = "System of measurement --- {Wikipedia}{,} The Free Encyclopedia",
    year = "2018",
    howpublished = "\url{https://en.wikipedia.org/w/index.php?title=System_of_measurement&oldid=860113814}",
    note = "[Online; accessed 28-September-2018]"
  }