Out of the blue: Vermeer's use of ultramarine in Girl with a Pearl Earring. - van Loon, Annelies; Gambardella, Alessa A.; Gonzalez, Victor; Cotte, Marine; De Nolf, Wout; Keune, Katrien; Leonhardt, Emilien; de Groot, Suzan; Proaño Gaibor, Art Ness; Vandivere, Abbie (Heritage Science, 2020)