Ah it's always a bit intimidating when someone says something is part of the essentials when you have yourself only seen a tiny bit of this course material in your program
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-> Each chapter starts with a personal anecdote and everything is repeated 3 times in 3 different ways. Lots of reassuring words that it's ok if you don't get it right away but trust the author that it will all make sense by the end of the book.
"Essential of coding theory"
-> University lecture with real world analogies for the students.
"Coding theory (5th Edition)"
-> Doorstopper. Mostly formulas and proofs. The text gives no clue of who and when.