This article theoretically explores the characteristics underpinning quadratic term structure models (QTSMs), which designate the yield on a bond as a quadratic function of underlying state variables.

Annie Qu, Bruce G. Lindsay, Bing Li, Improving Generalised Estimating Equations Using Quadratic Inference Functions, Biometrika, Vol. 87, No. 4 (Dec., 2000), pp. 823-836 ...