The Oxford Names Companion, OUP "Scottish Forenames" - Donald Whyte, FGH, FSG
Notes:
English and Italian, via Latin from Greek: "desired, loved".
Elmo was originally derived from various Old German names containing the element for "helm"; however it has now become an Italian pet name for Erasmus as has Ermo.
Thanks to Donald Whyte who provided much of the initial information for this site.