“…It is easy to see, in both cases above, their assumptions are stronger, in the sense that they imply that {M i,j } (i,j)∈N 2 is an orthomartingale, with the natural filtration {F i,j } (i,j)∈N 2 (1.4). On the other hand, however, the results in ( Basu and Dorea (1979); Poghosyan and Roelly (1998)) only assume that {ǫ i,j } (i,j)∈Z 2 is a stationary random field, which is weaker than our assumption.…”