In physics teacher education, one of the recurrent themes is the importance of fostering the formation of organised and coherent knowledge structures, but a simple shared understanding of what coherence actually means and how it can be recognised, is not easily found. This study suggests an approach in which the coherence of students' views about the relatedness of physics concepts can be identified and evaluated. Six pre-service physics teachers presented their understanding of the relatedness of physics concepts in the form of specially designed concept maps in which experimental or modelling procedures were required as links between physics concepts. The acceptability of the links was evaluated by using four criteria for epistemic analysis introduced in this study. The weighted values describing the maps' structural features were calculated, and finally, the cases were compared and the differences between them were discussed. The results show that the epistemic analysis of links affects remarkably to the acceptability of knowledge and thus also the coherence of such knowledge. The highest criterion set for acceptability seems to be very demanding to fulfil and even in the advanced level of studies only a fraction of students manage to reach it. The cases examined here show that the knowledge structures are partly fragmented and not as coherent as one would have expected them to be.