The strongest of sources might be a journal article that had been peer-reviewed. This means that domain experts had reviewed it and given their approval. However, such sources may often be too technical or not serve the purpose of the OBU report.
Another option might be to look at material that is read by industry professionals. For example, finance professionals will read the Financial Times and Bloomberg. As such, these information providers have to adhere to high standards of reporting and can be relied upon.
Professionals also read industry trade reports. For example, aerospace professionals will read reports by the International Air Transport Association (IATA).
Which industry are you exploring and have you checked the relevant trade associations?