Finding UN Documents by Symbol

If you have citation to a UN document that includes a symbol (some examples are: A/62/50 or ST/ADM/SER.B/517 or E/CN.4/2006/10/Add.2) go to UNBISnet, the United Nations Bibliographic Information System of the Dag Hammarskjöld Library, and search here.
Many UN document symbols start with a letter (the first component of the symbol which reflects the parent organ issuing the document or to which the document is being submitted):
A/- (General Assembly)
S/- (Security Council)
E/- (Economic and Social Council)
ST/- (Secretariat)
Coverage on UNBISnet is from 1979 onward, however, they are adding older documents on a regular basis.