The first reading is by Audrey Grant. She's a world reknowned bridge teacher. If you are interested in LOTT, go from pg 21. But the whole booklet is worth reading eventually.
https://www.abf.com.au/wp-content/uploads/2017/12/Modern-Competitive-Bidding-Handout.pdf
The second reading focuses more on "Jump raises in competition"
https://site.pianola.net/TinyFileManager/resources/files/178///l%205%20jump%20raises%20in%20competition%20notes%20and%20quiz.pdf