 A middle period from late 1982 to 1985 featured multi-panel paintings and individual canvases with exposed stretcher bars, the surface dense with writing, collage and imagery.The years 1984–85 were also the main period of the Basquiat–Warhol collaborations, even if, in general, they were not very well received by the critics.A major reference source used by Basquiat throughout his career was the book "Gray's Anatomy", which his mother had given him while he was in the hospital aged seven.