The cost model does not (except in exceptional circumstances under FC) affect whether the cost is direct or indirect (overheads). Usual stationery, office supplies etc are overheads, only special types of office supplies can be direct costs if it can be demonstrated that:
1. Used only on project
2. The accounting procedures of the organisation charge these as direct costs as a usual practice.
3. Are economic actual and necessary for project
4. Are “special” in nature – i.e. different from normal supplies
The same would apply to books, although frequently scientific books etc are specific to the field of the project and therefore more likely to be direct costs.