  Justification Awareness Models, JAMs, were proposed by S.~Artemov as a tool
for modelling epistemic scenarios like Russel's Prime Minister example. It was
demonstrated that the sharpness and the injective property of a model play
essential role in the epistemic usage of JAMs. The problem to axiomatize these
properties using the propositional justification language was left opened. We
propose the solution and define a decidable justification logic Jref that is
sound and complete with respect to the class of all sharp injective
justification models.
