Auburn University
Auburn University: A Glossary of Political Economy Terms: Complementary Goods
This site gives a good definition of "complementary goods" and provides examples. It also explains how when the price of Good A changes, the demand curve for Good B will shift.
Texas Education Agency
Texas Gateway: Chapter 4: Labor and Financial Markets: Review Questions
This is a list of eight review study questions covering the information in Chapter 4: Labor and Financial Markets.