The third source relating to localization economies is technological spillovers. The focal entity and receives or outflows know-how to others, creating incoming and outgoing spillovers. Specific announcements exert spillovers on other banks. Porter (1990), like MAR, argues that knowledge spillovers in specialized, geographically concentrated industries stimulate growth. Another example involves spillovers from credit markets to the goods market. Common applications include the analysis of social network spillovers and geographic spillovers. Substantial positive and negative spillovers limit the ability of any single jurisdiction to resolve issues. This is in contrast to MAR spillovers, which focus on firms in a common industry. This theory focuses on spillovers of integration, which leads to more integration. Construction and services, and to a lesser extent manufacturing benefit from these spillovers. Knowledge spillovers later were extended by economists Kenneth Arrow (1962) and Paul Romer (1986). There are two kinds of knowledge spillovers&colon; internal and external. One example involves spillovers from the labor market to the goods market. The river banks held and no spillovers occurred. The researcher must make specific assumptions about which types of spillovers are operative.