Asymptotic Properties of Minimum Norm and Optimal Quadratures. R.E. BARNHILL — 1968 Numerische Mathematik
Interpolation Remainder Theory from Taylor Expansions on Triangles. R.E. Barnhill; J.A. Gregory Numerische Mathematik
Sard Kernel Theorems on Triangular Domains with Application to Finite Element Error Bounds. R.E. Barnhill; J.A. Gregory Numerische Mathematik