In common usage, a collection is any group of items that has one or more properties in common. For example, paintings from the same artist, or coins from Germany before 1900, see collecting and collectible.
... diplomat, winner of the Nobel Peace Prize
April 16 - Fifi D'Orsay, actress (+ 1983)
April 22 - Robert Oppenheimer, physicist (+ 1967)
May 6 - Harry Martinson, ...