Elements
- 341
- USGS Minerals Information: Rhenium
- Statistics and information on the worldwide supply, demand, and flow of the element (PDF format).
- 342
- WebElements: Rhenium
- Extensive information on history, uses, occurrence, compounds, and properties.
- 343
- Wikipedia: Rhenium
- Properties of the element, including its history, applications, and characteristics.
- 346
- WebElements: Rhodium
- Extensive information on history, uses, occurrence, compounds, and properties.
- 347
- Wikipedia: Rhodium
- Properties of the element, including its history, applications, and characteristics.
- 351
- WebElements: Rubidium
- Extensive information on history, uses, occurrence, compounds, and properties of the element.
- 352
- Wikipedia: Rubidium
- Properties of the element, including its history, applications, and characteristics.
- 355
- WebElements: Ruthenium
- Extensive information on history, uses, occurrence, compounds, and properties.