The twentieth and twenty-first centuries have seen a great increase in the diversity in children's books, from picture books to flap books to online multimedia texts. In the 1960s, fantasy continued to dominate, perhaps due in part to the drug culture. In the 1970s and 1980s, children's literature became more materialistic and realistic. The 1990s saw an increase in the number of books dealing with social realism, such as Robert Swindells' Stone Cold (1994). In addition, the end of the twentieth century produced parodies of traditional folk tales, such as Fiona French's Snow White in New York (1986) and Jack Zipes' The Trials and Tribulations of Little Red Riding Hood (1993) and his collection of feminist fairy tales.