Unpublished sources of external strategic information include all of the following EXCEPT:

The correct answer is that unpublished sources of external strategic information do not include abstracts. Abstracts typically summarize existing research findings and published literature across various fields. They serve as a concise overview of published studies, thus they are part of published sources rather than unpublished ones.

In contrast, market research, conversations with stakeholders, and customer surveys represent methods through which organizations can gather firsthand insights and data that are not officially published. Market research often involves gathering information about potential customers and market trends; conversations with stakeholders can yield valuable qualitative data; and customer surveys provide direct feedback from users about products or services. These methods contribute to a deeper understanding of the external environment and strategic positioning, distinct from the summarized reports that abstracts present.