His main achievement was the great international Frans Hals exhibition in 1962 and the scientific catalog that he published with it, that had contributions by Carla van Hees and the young Seymour Slive.
Petrus Camper | Petrus Plancius | Petrus | Petrus Ramus | Petrus Christus | Lars Petrus | Jacobus Henricus van 't Hoff | Henricus Hondius | Jacques Fred Petrus | Petrus Van der Velden | Petrus Hofstede de Groot | Petrus de Natalibus | Petrus Codde | Petrus Canisius van Lierde | Petrus Astronomus | Petrus Alphonsi | Petrus Alfonsi's Tetragrammaton | Joseph Petrus Hendrik Crowe | Johannes Henricus Gerardus Jansen | Janus Henricus Donker Curtius | Ioannes Henricus Meibomius | Henricus Aeneae | Baard Slagsvold |