Knowledge markets may also be sequential in nature. Simard (2006) describes a cyclic knowledge-market model comprising nine stages that embed, advance, or extract value into knowledge products and services along a knowledge services value chain. The first five stages are internal to a knowledge organization (production and transfer) while the last four stages are external (intermediaries, clients, and citizens). Because the value chain is cyclic, it can be used to model either a supply (post-production evaluation ) or a demand (pre-production evaluation) approach to knowledge markets.