https://www.bitcoin.com/get-started/how-bitcoin-transactions-work/
https://en.bitcoin.it/wiki/Block
https://developer.bitcoin.org/devguide/block_chain.html
https://statoshi.info/d/000000017/fee-estimates?orgId=1
https://en.bitcoin.it/wiki/Miner_fees#Fee_Plotting_Sites
https://bitcointalk.org/index.php?topic=81626.20
https://en.bitcoin.it/wiki/PHP_developer_intro
https://github.com/cryptoapi/Payment-Gateway
https://developer.bitcoin.org/examples/testing.html
https://github.com/dryphp/bitcoin.php/blob/master/src/bitcoin.inc
https://wiki.uniformserver.com/index.php/SSL_PHP_Server_Key_and_Certificate_generation
https://www.ellipal.com/blogs/support/calculate-bitcoin-miners-fee
https://bitcoinops.org/en/tools/calc-size/
https://news.bitcoin.com/how-to-calculate-bitcoin-transaction-fees-when-youre-in-a-hurry/
