On the critical examination of the "field-theoretical approach" to the   neutron-antineutron oscillations in nuclei
  We briefly outline the models of the $n\bar{n}$ transition in nuclei and analyse a well known calculation based on diagram technique published in 1992 and repeated recently by V. Kopeliovich and I. Potashnikova. 
V.I.Nazaruk
hep-ph nucl-th