Advertising and Affiliate Disclosure

Last updated: 2026-07-12

Affiliate Links

The English section currently uses Udemy affiliate links when introducing relevant online courses. Amazon.co.jp affiliate links are not used on English pages.

Disclosure

Affiliate sections will be marked with labels such as "PR", "Ad", or "Sponsored". Links will use rel="sponsored nofollow" where appropriate.

Selection Policy

• Materials are selected based on relevance to quiz topics and likely learning value.
• Affiliate reward availability does not guarantee a recommendation.
• Final purchasing decisions should be made by the user after checking price, edition, and reviews.