Walk, Manfred. "3. Dual problems of optimization". Theory of Duality in Mathematical Programming, Berlin, Boston: De Gruyter, 1989, pp. 78-173. https://doi.org/10.1515/9783112483442-004
Walk, M. (1989). 3. Dual problems of optimization. In Theory of Duality in Mathematical Programming (pp. 78-173). Berlin, Boston: De Gruyter. https://doi.org/10.1515/9783112483442-004
Walk, M. 1989. 3. Dual problems of optimization. Theory of Duality in Mathematical Programming. Berlin, Boston: De Gruyter, pp. 78-173. https://doi.org/10.1515/9783112483442-004
Walk, Manfred. "3. Dual problems of optimization" In Theory of Duality in Mathematical Programming, 78-173. Berlin, Boston: De Gruyter, 1989. https://doi.org/10.1515/9783112483442-004
Walk M. 3. Dual problems of optimization. In: Theory of Duality in Mathematical Programming. Berlin, Boston: De Gruyter; 1989. p.78-173. https://doi.org/10.1515/9783112483442-004