Firms in local industries maintain their capability to generate new export varieties by simultaneously exploiting internal and external knowledge resources. The paper introduces the notion ‘variety triplet’ to distinguish individual export varieties, where a triplet is a unique combination of a firm, a product code and a destination country. For each date, the set of variety triplets in each local industry records all remaining export varieties introduced in the past. In view of this, the paper examines how internal and external knowledge of local industries influence the industry's scope and value of export varieties. First, the paper contributes by considering a local industry's internal and external knowledge, as well as the conjunction of its internal and external knowledge sources. Second, the knowledge sources are shown to influence both the stock and the dynamics of a local industry's variety triplets, using firm-level data from Sweden.