Deception includes falsifying information, obscuring the truth, and lying in order to manipulate public opinion about the historical event discussed in the revised history. The negationist historian applies the techniques of deception to achieve either a political or an ideological goal, or both. The field of history distinguishes among history books based upon credible, verifiable sources, which were peer-reviewed before publication; and deceptive history books, based upon unreliable sources, which were not submitted for peer review.[20] The distinction among types of history books rests upon the research techniques used in writing a history.