Company strategy often plays out over long periods of time. You can often gather evidence by reading longer articles in newspapers, trade, and industry magazines. Trade and industry magazines can be found in Business Source Complete and ABI/INFORM Collection databases.
Here are my top resources for quickly finding company strategy articles.
Databases can also yield company strategy articles; below is a search strategy for Business Source Complete to find strategy articles. It will work for other databases similarly. You can add functions (finance, management, products and services, sales and marketing, etc.) to find more focused articles.