Elements
- 303
- WebElements: Phosphorus
- Extensive information on history, uses, occurrence, compounds, and properties of the element.
- 304
- Wikipedia: Phosphorus
- Properties of the element, including its history, applications, and characteristics.
- 307
- WebElements: Platinum
- Extensive information on history, uses, occurrence, compounds, and properties.
- 308
- Wikipedia: Platinum
- Properties of the element, including its history, applications, and characteristics.
- 309
- Chemical Elements.com - Plutonium (Pu)
- Information on the chemical properties of plutonium, as well as its electron cloud diagram.
- 311
- The Actinide Research Quarterly: Winter 1997 : On the Disposal of Plutonium
- An article that is an interview with a leading scientist on the disposal of plutonium.
- 315
- Wikipedia: Polonium
- Properties of the element, including its history, applications, and characteristics.
- 318
- WebElements: Potassium
- Extensive information on history, uses, occurrence, compounds, and properties of the element.