Economic use of knowledge--Resources in use: embedded electricity--Introducing old knowledge in a established user context: how to use wood in the construction industry--Conscious use of others interface knowledge: how IKEA can keep the price of the lack table constant over decades--Handling resource interfaces in a planned economy: how tipografiya solves interaction issues without direct interaction--Use of knowledge in the model world: lessons to learn from economic literature--Interaction: the only means create use.