The link for Backup_and_Recovery_Approaches_Using_AWS is achieved in 2016

Hi Jaeyoung,
  You need to download the resources from inside the lecture, not from the dashboard.

Also always check the AWS site for more up to data doco or new releases. It probably won’t make any difference on the exam, but as a you go into real jobs you want to be familiar with where to find the most recent information at any time. 

Moderator & Coach

P.S.  I will ask the Content team to check that these are the most recent white papers, but in the meantime you can take control by checking the web site.