I wouldn’t expect un biased as this is impossible. I’d rather look for nuanced takes who say that they did something bad, but examine why they did it and if it was necessary.
And you must always be critical of what anyone says and thinks even yourself. It’s ruthless criticism of all that exists after all.
As to spesific sources I don’t have any that are available as E-books. I mostly have local pamphlets and papir books printet by my or other communist groups or partyes
Did they forget the one underneath?