How to fill gaps in C#/Unity3d knowledge?

Question

Books

Question No. 1: I
studied C# on the Internet from various videos in the style of: "How to learn C# in an hour", "What are variables", "OOP basics".
Now I have a good understanding of this language at a basic level (I think, almost June), I can write simple programs.
Can you suggest literature to fill in the gaps?
But there are a couple of nuances:
1) I do not want to learn again what cycles, variables, etc. are.
2) I obviously do not reach the literature above average in the style of "For professionals".
Question number 2
I have the same problem with Unity (I studied this engine in fragments, like C#, so I need literature to fill in the gaps. Preferably not Unity manuals, something more structured, because there, in fact,
You can answer only one question or combine them.

Answer 1

According to Unity, in addition to documentation, the main learning resource is learn.unity.com
There is a paid option for comfortable learning.