There are quite a few issues with that.  Books are less verifiable than web links.  To be clear, Government funded sources include academia, and they are also less verifiable if not freely accessible.  What makes basic income special is that, unlike virtually every other political proposition, the Champion of basic income gains no privilege whatsoever over other citizens, and so the only reason to champion UBI is to provide freedom and dignity to everyone.  The relevance is that there is no business model for power accumulation behind it, and that affects the sources available.  Limiting information sources to entrenched power sources (Government, academia and corporate) stacks the deck with biased point of view in favour of power structures, or in the case of the state of this page, makes it impossible to describe UBI.  There is great content available on the web for UBI.  Academic work is more timid, less accessible, and often of lower quality than other research on UBI.