Tratar vs tratarse (de, sobre)

[fglorca]

Are the following three correct:

1. El libro trata de la guerra civil.
• The book is about the civil war.

2. El libro trata sobre la guerra civil.
• The book deals with (addresses) the civil war.

3. En el libro se trata la guerra civil.
• In the book the civil war is dealt with (addressed). [Passive]

I think the two below are grammatically incorrect, but would appreciate confirmation of this:
1. El libro se trata de la guerra civil
2. El libro se trata sobre la guerra civil.
• The book deals with the civil war.

But I think we can say:
1. Se trata de la guerra civil.
2. Se trata sobre guerra civil.

However, I’m not sure why the above two are correct, or how to translate them.
Many thanks in advance.