... Difference Equations 12 R Yuan, On the spectrum of almost periodic solution of second-order differential equations with piecewise constant argument,” Nonlinear Analysis: Theory, Methods & Applications, ... to: On the spectrum of almost periodic solution of second order scalar functional differential equations with piecewise constant argument”,” Journal of Mathematical Analysis and Applications, ... R Yuan, On the module containment of the almost periodic solution for a class of differential equations with piecewise constant delays,” Journal of Mathematical Analysis and Applications, vol...