Models of paper as a network structure and as a laminate of cell wall layers, with inclusions containing air, are compared with respect to their abilities to describe the elastic properties of paper. The effects of sheet density on the dynamic elastic modulus of papers of a bleached sulfate pulp are compared with the predictions of the two theories. At high density, the net work model approaches that of the continuum structure. Both the network model and the continuum model, when accounting for maximum inclusion of air into the paper, produce stiffness-density curves in accordance with experiments. -- AATA