diff --git a/README.md b/README.md
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@@ -824,6 +824,7 @@ An updated and organized reading list for illustrating the patterns of scalable,
 * [Media Database at Netflix](https://medium.com/netflix-techblog/implementing-the-netflix-media-database-53b5a840b42a)
 * [Member Transaction History Architecture at Walmart](https://medium.com/walmartlabs/member-transaction-history-architecture-8b6e34b87c21)
 * [Sync Engine (2 parts) at Dropbox](https://dropbox.tech/infrastructure/-testing-our-new-sync-engine)
+* [Ads Pacing Service at Twitter](https://blog.twitter.com/engineering/en_us/topics/infrastructure/2021/how-we-built-twitter-s-highly-reliable-ads-pacing-service)
 * [Architectures of Finance and Banking Systems](https://www.sesameindia.com/images/core-banking-system-architecture)
 	* [Bank Backend at Monzo](https://monzo.com/blog/2016/09/19/building-a-modern-bank-backend/)
 	* [Trading Platform for Scale at Wealthsimple](https://medium.com/@Wealthsimple/engineering-at-wealthsimple-reinventing-our-trading-platform-for-scale-17e332241b6c)