In 1967 , he revised the nomenclature of the four groups .
Holger Kapel classified 68 Paleolithic sites into four cultural groups based on flint typology , designating letter terms to each group , in 1964 .
In 1967 , Holger Kapel revised the nomenclature of the four groups .
Holger Kapel classified 68 Paleolithic sites into four cultural groups based on flint typology , designating letter terms to each group , in 1964 .