The second contribution towards localization economies is the access to specialized goods and services provided for the clustering firms. This access to specialized goods and services are known as intermediate inputs and provides increasing returns to scale for each of the firms located within that area because of the proximity to available sources needed for production. If intermediate inputs are tradable, there forms a core-periphery notion that will have many firms locate near each other to be closer to their needed sources. If there are tradable resources and services nearby but no related industries in the same area, there are no networking linkages and therefore makes it difficult for all firms in the area to obtain resources and increase production. The decreased transportation costs associated with clustering of firms leads to the increase in likelihood to a core-periphery pattern; where the result of this will be more intermediate inputs will be focused at the core and therefore will attract more firms in related industries.