Spring Javadoc

https://docs.spring.io/spring-framework/docs/current/javadoc-api

Spring Reference

https://docs.spring.io/spring-framework/docs/current/reference/html

Chapter 2. Getting Started

Chapter 3. Introducing IoC and DI in Spring

Chapter 4. Advanced Spring Configuration and Spring Boot

Chapter 6. Spring Data Access with JDBC

Chapter 18. Monitoring Spring Applications