Ivan Roitt was born in 1927.

Peter J. Delves has written:

'Roitt's essential immunology' -- subject- s -: Immunology, Immunity, Immune System

'Cellular Immunology LabFax'

Ivan the Great (Ivan III)

then Ivan the terrible (Ivan IV)

Ivan the Great came first

Ivan IV, the Terrible, was the grandson of Ivan III, the Great.

Grandfather actually.

Ivan III (Ivan the Great) did have a son named Ivan but he was called Ivan the Young and did not rule. Ivan the Great was succeeded by his eldest son Vasili III who was then succeeded by his son Ivan IV (the Terrible).