Galerie Burén in Stockholm (run by Eva af Burén) organized significant solo exhibitions in 1968. Sivert's exhibition at the gallery that year attracted considerable attention. It was there that he first showcased his "multiples" featuring his own body profile, standing full-figure and rotated 360 degrees, cast in white plastic. These, along with his miniature face profile. This is reproduced as a multiple impression in a block of white plastic and sometimes orange-yellow plastic. A multiple is actually a number in mathematics that can be divided by another number an even number of times (without a remainder). / JÖ