Abstract
<snipped for conciseness>
https://www.ncbi.nlm.nih.gov/pubmed/12056428
Published in 1963, five years before the first mission beyond LEO, and, as it says in the title and notes in the abstract, is discussing
estimates of likely doses. What additional information was available by the time Apollo 8 was launched, and what conclusions were drawn from it? Have you looked in detail at the refinement of measurements and modelling of the radiation environment since the beginning of space flight?
Also, on my reading of the abstract, it implies that with proper shielding and routing, missions beyond LEO should not present unsurvivable hazards. I'll leave discussion of the actual estimated doses and shielding to people who understand these things better than I do.
I would also ask, what further detail is provided in the full paper? You shouldn't base any discussion or conclusions purely on the abstract. Again, not being an expert in this area I won't go through it myself, but if you're going to be discussing estimates, measurements and analysis of the radiation in space, you need to do more than copy a few abstracts or selected graphs - you need to do a proper literature search and take the time to read, understand, and where necessary, analyse the data.