“…A trace formula of a differential operator has many applications in the inverse problem, in the numerical calculation of eigenvalues, in c 2012 Verlag der Zeitschrift für Naturforschung, Tübingen · http://znaturforsch.com the theory of integrable systems, etc. Sadovnichii and Podol'skii [11] stated several sharp methods to trace formulae of second-order operators, high-order operators as well as partial differential operators. Using Rouché's theorem for operator-valued functions in [12], we can suitably locate the eigenvalues of L(Q, M; h, H) and find a precise description for the formula of the square root of the large eigenvalues up to the o( 1 n )-term, which are similar to the results in [1,2]:…”