How to cite statements in book based on unverifiable sources

Question

While reading books on Indian politics (not aware if this happens outside as well), frequently the citations for a particular claim is some interview with a person being talked about. In this case, one reading the book can trust the statement only if he personally gives his belief to the author's word. This is OK if the reader personally believes in the integrity of author but this becomes problematic in debate since we cannot ask other side to trust an author for his unverifiable account if author is not well-known or known for political bias, these are genuine misgivings and I feel the one using these books must be the one to mitigate such concerns

In this case, how should we present a statement/claim in a manner that acknowledges possible ambiguity and unverifiablilty or should one abstain from this practice and cite only authors recognized by both sides as reputable??

Some particular examples are:

1. In the book "India after Gandhi", Ramchandra Guha cites some anonymous accounts.
2. In the memoir "Accidental Prime-Minister", Sanjay Baru has exclusively put his opinions and done away with citations and references.
3. The current book I am reading, Half - Lion: How P.V Narasimha Rao Transformed India also contains many citations in form of personal interviews conducted by the author

Answer 1

The technical answer to your question ("how to cite") is that you cite the book the same way you cite any other book, following the citation guidelines of the publication to which you're submitting.

However, your actual question seems to be more focused on how to ensure you don't mislead readers into thinking your sourced quotes are stronger than they really are. I don't think there's a definitive answer here. My recommendation would simply be to tell the reader that the cited source is based on personal claims. For example:

Based on personal conversations, Michael Wolff has stated that Steve Bannon does not drink alcohol [22].

[22] Wolff, M. "Fire and Fury: blabbidy blab". Publisher. Page whatever.

Answer 2

You should simply acknowledge the limits of verifiability and cite the source. There is no question of finding sources that are acceptable to 'both sides', because you cannot possibly know every reader's leanings. Also, choosing to cite individuals because they are 'reputable' seems to be rather unscientific and will only further selection bias.

(1) The available literature, primarily derived from personal conversations, suggests that this statement is true [ref].

(2) This statement is derived from the partly anonymous accounts provided by Guha in [ref].

(3) Interviews conducted and provided by Rao [ref] suggest that this statement is true.

(4) On the basis of opinions provided by Baru [ref], it appears reasonable to accept this statement as true.