Buying a Printed Book Online in 2021
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I did an exam simulation yesterday, and failed. Thanks goodness I do not
go to school anymore, and can get more chances to do the exams. After 
submitting the exam, I can go back and see in which of the questions I've 
failed and in which I've succeeded.
I can also read a detailed explanation of the correct answers and why
other options are wrong.
There are references at the bottom of the page, with the chapter's
number and a link to a page in Amazon from which I can purchase the
relevant book.
I ordered a printed edition of the book. There's also a Kindle version
of the book, which is cheaper and does not require shipping by
air-mail. Since I don't have a Kindle device, I ordered a printed book,
and when I buy book I always buy them new. I got notified by Amazon and by 
the Postal Authority in my country that my order has been shipped. 
I hope I will get it soon, start getting 100% grades, and pass the
exam.