Online sources
- Air Masses and Frontal Transitional Zones (PhysicalGeography.net)
- Air Masses and Fronts (University of Illinois)
- Interpreting Weather Charts (Met Office Fact Sheet No. 11)
- Mid-latitude Fronts and Cyclones (University of Wisconsin-Madison)
- The Mid-Latitude Cyclone (PhysicalGeography.net)
- Weather Systems (Kean University, New Jersey)