Business Tutorials: Database Tutorials

Business Insights

Business Source Premier

IBISWorld

Investext (via Mergent Online)

Mergent Online

Mintel

Passport

Portland Business Journal

PrivCo

Reference Solutions (previously ReferenceUSA)

The following is a list of documents from the publisher on their methodology behind the numbers: 

RIA Checkpoint

Simmons Insights

SMA (Sports Market Analytics)

Statista

WRDS (Wharton Research Data Services)