• BIP 68 Relative lock-time using consensus-enforced sequence numbers
• BIP 112 (CHECKSEQUENCEVERIFY) - describes also use cases - htlc, bidirectional payment channels and the Lightning Network, requires BIP68
• BIP 113 Median time-past as endpoint for lock-time calculations

• original LN whitepaper: https://lightning.network/lightning-network-paper.pdf

• a series of articles covering many aspects of LN:

  • https://bitcoinmagazine.com/articles/understanding-the-lightning-network-part-building-a-bidirectional-payment-channel-1464710791/
  • https://bitcoinmagazine.com/articles/debunking-the-most-stubborn-lightning-network-myths-1444837807/
  • https://bitcoinmagazine.com/articles/does-the-lightning-network-threaten-bitcoin-s-censorship-resistance-1462904079/
  • http://bitcoinschannel.com/lightning-how-payment-channels-build-up-a-network/

• cross blockchain trades/atomic swaps: http://www.coindesk.com/cross-blockchain-trades-lightning-gives-new-life-atomic-swaps/

• documentation of the current protocol implementation: https://github.com/lightningnetwork/lightning-rfc

• very recommended highlevel view of the current spec by Rusty Russel: https://medium.com/@rusty_lightning/the-bitcoin-lightning-spec-part-1-8-a7720fb1b4da

• limitations and other issues: https://medium.com/@rusty_lightning/bitcoin-lightning-things-to-know-e5ea8d84369f

• Rusty Russell's blog describing LN: https://rusty.ozlabs.org/?p=450

• THE WIKI - terminology: https://en.bitcoin.it/wiki/Lightning_Network

• setting up and testing with a faucet (free giveaway of coins through LN channel): http://lightning.community/lnd/faucet/2017/01/19/lightning-network-faucet/

• Elements project: https://github.com/ElementsProject/lightning/tree/master/doc

mkdir ln-example
cd ln-example
virtualenv .venv
git clone https://github.com/braiins/lnd
. .venv/bin/activate
cd lnd/docker
git checkout -b ltc-rebased-master origin/ltc-rebased-master
source conf/bitcoin

And follow the README.md and start charlie too:

docker-compose up -d --no-recreate charlie
docker exec -ti btc_charlie /bin/bash