A friend just asked me to send him information so he can learn about bitcoin. So far I sent nostr:nprofile1qqsw4v882mfjhq9u63j08kzyhqzqxqc8tgf740p4nxnk9jdv02u37ncpz3mhxue69uhkummnw3e8xct5wesjumn9wsq3vamnwvaz7tmjv4kxz7fwwpexjmtpdshxuet59aktc5 Nothing Stops this train and told him to buy the Bitcoin standard and read it. Any other recommendations on what I should send him?