1. Balan TT (1970) Observatii asupra functionalelor supra-aditive. Analele Univ. Craiova 1
2. Balan TT (1992) Generaling the Minkowski space-time (I) and (II). Stud Cerc Math Tom 44, 2:89?107
3. Ball JM (1976?77) Convexity conditions and existance theorems in nonlinear elasticity. Arch Rat Mech Anal 63:337?403
4. Birkhoff G (1946) Tres observationes sobre el algebra lineal. Revista Facultad de Ciencias Exactas, Puras y Applicadas Universidad National de Tucuman, Serie A (Mathematicas y Fisica Teorica) 5:147?151
5. Calvaire B (1991) Strictly plus functionals on a super-additive normed linear space, Technical paper, Aucland University