"Blinken: ismét mozgásban", 1995. HU OSA 367-0-1-671; Donald Blinken Ambassadorial Files; Open Society Archives at Central European University, Budapest.
When you cite the online source, the phrase "[Electronic record]" should be inserted into the standard citation after the item title and date. The citation should be followed by the URI with the date you last accessed the resource in square brackets.