Correct. Bitcoin is not mentioned in the Libra Whitepaper ...

- https://libra.org/en-US/wp-content/uploads/sites/23/2019/06/LibraWhitePaper_en_US.pdf

However, it is mentioned in the Libra Blockchain paper ...

- https://developers.libra.org/docs/assets/papers/the-libra-blockchain.pdf

Pages. 4, 6, 10 and 14 as well as in the References ...

[23]
“Leaf-node weakness in Bitcoin merkle tree design,”
https://bitslog.com/2018/06/09/leaf-node-weakness-in-bitcoin-merkle-tree-design/ .
[24]
S. Nakamoto, “Bitcoin: A Peer-to-Peer Electronic Cash System,”
https://bitcoin.org/bitcoin.pdf, 2008.

...

Regina Spektor - "Us"
- https://youtu.be/fczPlmz-Vug