https://www.amazon.co.uk/Scalability-Startup-Engineers-Artur-Ejsmont-ebook/dp/B00ZPS4KI0/ref=tmm_kin_swatch_0?_encoding=UTF8&qid=1606169098&sr=8-1
This is a good book that I told you about
https://www.amazon.co.uk/Infrastructure-Architecture-Building-Blocks-Concepts-ebook/dp/B01N9ZC7H3/ref=tmm_kin_swatch_0?_encoding=UTF8&qid=1606169303&sr=8-1
A brilliant book about infrastructure, non functional requirements (performance,secrutiy, availability), devops, and hardware
https://www.amazon.co.uk/Software-Architecture-Practice-Engineering-Hardcover/dp/0321815734/ref=sr_1_1?dchild=1&keywords=software+architecture+in+practice&qid=1606169420&sr=8-1
Good book about architecture, and lots of info on non functional requirements (availability, performance, interoperability, secruity, testability)
https://www.amazon.co.uk/Head-First-Design-Patterns-Brain-Friendly-ebook/dp/B00AA36RZY/ref=tmm_kin_swatch_0?_encoding=UTF8&qid=1606170146&sr=8-4
A friednly intro to design patterns
https://bigmachine.io/products/the-imposters-handbook/
A book about computer science topics
"The unicorn project" and "the phoenix project", are good reads and novels about development and devops
https://www.amazon.co.uk/Cracking-Coding-Interview-6th-Programming/dp/0984782850/ref=sr_1_1?crid=Q071638RBO9P&dchild=1&keywords=cracking+the+coding+interview&qid=1606169966&sprefix=cracking+the+cod%2Caps%2C156&sr=8-1
About interviews, but lots of computer science q&A
https://www.amazon.co.uk/Refactoring-Improving-Existing-Addison-Wesley-Signature-ebook/dp/B07LCM8RG2/ref=tmm_kin_swatch_0?_encoding=UTF8&qid=1606169621&sr=8-1
The bible of different refactoring techniques. Although you can get alist of these on line (https://sourcemaking.com/refactoring)
https://reflectoring.io/book/
This is a good book on clean architecture, a more robost arhitecture compared to MVC
https://www.amazon.co.uk/Real-World-Software-Development-Project-Driven-Fundamentals-ebook/dp/B0828B1HGH/ref=sr_1_1?crid=2EOJFWHQL7S4E&dchild=1&keywords=real-world+software+development&qid=1606169160&sprefix=real+world+soft%2Caps%2C156&sr=8-1
A good book about coding and ideas of coding and engineering via examples
I dont know a good resource, but learning SQL is essential in backend engineering
Network is also important to understand, http, https, tcp/ip, dns, load balancing, proxy, websockets, cookies
Good podcasts/videos: