
## API Keys Required

Some providers may require API keys to retrieve papers, articles, and other forms of data. Known providers requiring keys include:

- ***: For scientific articles
- **Springer Nature**: For scientific content  

Others may require the use of a `User Agent`, including:

- ***: Crossref API (Also recommends adding a `mailto:` header for feedback for usage)
- ***: Plos API
- ***: CORE API

## ⚠️ Data Usage and Legal Compliance

**Important**: This software is licensed under Apache 2.0, but this license **only covers the code itself**. 

### Your Responsibilities

When using this package, you must:

- ✅ Obtain your own API keys from each data provider
- ✅ Read and comply with each provider's terms of service
- ✅ Respect rate limits and usage restrictions
- ✅ Ensure your use complies with copyright laws
- ✅ Handle data according to applicable privacy regulations

## License

This project is licensed under the Apache License 2.0 - see the [LICENSE](LICENSE) file for details.

**Data License**: Data accessed through APIs is subject to the respective providers' terms of service - see the [NOTICE](NOTICE) file.
