KOTLIN https://javarush.com/groups/posts/2003-kotlinrush-a-estjh-li-smihsl-prodolzhatjh-pisatjh-na-java?post=full#discussion

Сходства и различия интерфейсов и абстрактных классов https://javarush.com/groups/posts/431-10-voprosov-po-abstraktnihm-klassam-i-interfeysam-s-sobesedovaniy-po-jazihku-java?post=full#discussion

REST https://javarush.com/groups/posts/2486-obzor-rest-chastjh-1-chto-takoe-rest

Сетевое взаимодействие https://javarush.com/groups/posts/2514-vvedenie-v-enterprise-razrabotku

Паттерны(кратко) Паттерн Observer Паттерн MVC Паттерн MVVM Паттерн MVP MVP

Clean Architecture в Android https://medium.com/nuances-of-programming/clean-architecture-%D0%B2-android-%D0%B4%D0%BB%D1%8F-%D0%BD%D0%B0%D1%87%D0%B8%D0%BD%D0%B0%D1%8E%D1%89%D0%B8%D1%85-f44d25495f5b

Принципы SOLID https://javarush.com/groups/posts/osnovnye-principy-dizajna-klassov-solid-v-java?post=full#discussion

HTML http://citforum.ru/internet/html3.2ex/index.shtml http://htmlbook.ru/html

SQL https://www.sqltutorial.org/sql-cheat-sheet/

JUnit тесты https://javarush.com/groups/posts/605-junit