For Stage 4-5 in the Week 7 Legendary Quests in Fortnite Battle Royale, you need to “Collect Parenting Books from Holly Hatchery or Retail Row”. There are a few different book locations in both Holly Hatchery and Retail Row but you only need to collect two of them to complete this stage of the quest. You can easily find two of them in the buildings pictured below, simply head into them to find the Parenting Books. Alternatively a video has been included if you prefer a visual walkthrough.
For some reason, the Parenting Books may not spawn. If this is the case simply go into another game and it should be there for you.