Abstract: The apparatus comprises a post having a floor-engaging base, an arm having its rear end pivotally connected to the top of said post for horizontal swinging movement, a connector pivoted to the front end of the arm for rotation about a vertical axis, said connector defining a rearwardly- upwardly-inclined plate-like element having upwardly-converging side edges which are also rearwardly converging thicknesswise of the plate-like element. A reading material support plate, having a bottom ledge, is provided at its back face with a pair of flat, elongated retainer elements which define between themselves a series of cavities with upwardly-converging side edges, which are also rearwardly converging thicknesswise for mating with and selectively receiving the plate-like element of the connector. It is a simple matter to insert the plate-like element in a selected cavity. The support plate is thus supported at a selected level and prevented from detachment from the connector.