Analysis of information sources in references of the Wikipedia article "Raven paradox" in English language version.
Nicod had proposed that, in relation to conditional hypotheses, instances of their antecedents that are also instances of their consequents confirm them; instances of their antecedents that are not instances of their consequents disconfirm them; and non-instantiations of their antecedents are neutral, neither confirming nor disconfirming.