Abstract: A book receptacle mounted on wheels forms a movable book storage container. Within the book receptacle is a collapsible container with an upper peripheral edge which is affixed to the upper edge of the support structure of the book receptacle. The collapsible container in an uncollapsed state substantially fills the volume defined by the support structure. A load-responsive support, which is preferably an elastic cord, provides load-responsive support between a first attachment point located at the bottom of the collapsible container and a second attachment point located on the support structure and spaced from the first attachment point so that the collapsible container is held in a substantially collapsed condition when the container is empty and expands to substantially fill the volume defined by the support structure as additional books are added.