George Catlin, Illustrations of the manners, customs… (1876)
“ THE CHINOOKS. Inhabiting the lower parts of the Columbia, are a small tribe, and correctly come under the name of Flat Heads, as they are almost the only people who strictly adhere to the custom of squeezing and flattening the head. Plate 209, is the portrait of a Chinook boy, of fifteen or eighteen years of age, on whose head that frightful operation has never been performed. And in plate 210, will be seen the portrait of a Chinook woman, with her child in her arms, her own head flattened, and the infant undergoing the process of flattening ”
