Have you read this page on the use of arxiv which basically says it can be alright to use it as a source Apart from that the 2 papers mentioned in the In line notes and references section have been published in peer reviewed journals but link to the arxiv version and of the 5 arxiv links in the Further reading 2 have also been published in journals 1 also in a conference proceedings and 1 also as a book of lecture notes This looks like potentially quite good sourcing to me Whether the content of the article matches the information contained in the sources is another matter