Amazon Sponsored products - Books not eligible?

Hi all,

Just tried to start an Amazon sponsored products campaign but it seems you can’t promote books, why is this please?

I’m afraid that books are not supported category for Sponsored Products.
Sponsored Products is only available in the following Amazon search categories:
• Baby
• Beauty
• Car & Motorbike
• Clothing
• Computers & Accessories
• DIY & Tools
• Electronics & Photo
• Film & TV
• Garden & Outdoors
• Grocery
• Health & Beauty
• Jewellery
• Kitchen & Home
• Large Appliances
• Lighting
• Music
• Musical Instruments & DJ
• PC & Video Games
• Pet Supplies
• Shoes & Accessories
• Software
• Sports & Outdoors
• Stationery & Office Supplies
• Toys & Games
• VHS
• Watches
• Business, Industry & Science