Feynman diagrams for the leading order contribution to the fluctuation conductivity of granular metals. Wavy lines are fluctuation propagators corresponding to Cooper pairs, solid lines with arrows are normal-state Green’s functions corresponding to normal state quasi-particles, and shaded semicircles are vertex corrections arising from impurities. Dashed lines with central crosses are additional impurity renormalizations and shaded blocks are impurity ladders. Diagram 1 is the Aslamazov–Larkin (AL) contribution, diagram 2 is the Maki–Thompson (MT), and diagrams 5–8 are the density of states (DOS). Diagrams 3, 4, and 9, 10 arise when one averages the DOS and MT diagrams over impurities.