Reading summary

Summarize the video lectures:

1. https://youtu.be/wySXLRTxAGQ?list=PLtBw6njQRU-rwp5__7C0oIVt26ZgjG9NI

2. https://www.youtube.com/watch?v=nZfaHIxDD5w&list=PLtBw6njQRU-rwp5__7C0oIVt26ZgjG9NI&index=27