1. M. Bohner: Zur Positivität diskreter quadratischer Funktionale. Dissertation, Ulm, (1995).
   2. M. Bohner, O. Došlý: 
Positivity of block tridiagonal matrices. SIAM J. Matrix Anal. Appl. 20 (1999), 182–195. 
MR 1644495   3. M. Bohner O. Došlý, W. Kratz: 
An oscillation theorem for discrete eigenvalue problems. to appear. 
MR 2052485   4. G.H. Golub, C.F. Van Loan: 
Matrix computations. John Hopkins University Press, Baltimore, (1983). 
MR 0733103 | 
Zbl 0559.65011   5. R.A.Horn, C.A. Johnson: 
Matrix analysis. Cambridge University Press, Cambridge, (1991). 
Zbl 0729.15001   6. W. Kratz: 
Quadratic functionals in variational analysis and control theory. Akademie Verlag, Berlin, (1995). 
MR 1334092 | 
Zbl 0842.49001   7. W.T. Reid: 
Sturmian theory for ordinary differential equations. Springer Verlag, New York, (1980). 
MR 0606199 | 
Zbl 0459.34001   8. H.R. Schwarz H. Rutishauser, E. Stiefel: Numerik symmetrischer Matrizen. Teubner Verlag, Stuttgart, (1972).