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.
Auburn University
Auburn University: A Glossary of Political Economy Terms: Substitute Goods
Dr. Johnson thoroughly explains the concept of "substitute goods," and how a price increase of one good will shift the demand curve for a substitute good.
Tutor2u
Tutor2u: Shifts in Market Demand
This is an easy to understand site that presents the law of demand, changes in quantity demanded, and the factors that cause a demand curve to shift. It also discusses how inferior goods and normal goods respond to changes in demand.
Curated OER
Market Demand for Goods and Services
This is an easy to understand site that presents the law of demand, changes in quantity demanded, and the factors that cause a demand curve to shift. It also discusses how inferior goods and normal goods respond to changes in demand.