[x] I have searched the PRs of this repo and believe that this is not a duplicate.
Moved PHANTOM to appropriate section. Added SPECTRE:
- **Title**: SPECTRE: A Fast and Scalable Cryptocurrency Protocol
- **Link**: https://allquantor.at/blockchainbib/pdf/sompolinsky2016spectre.pdf
- **Category**: DAG
Checklist for submitting a pull request to
blockchain-papers
: