@article{article6bc5f85d,
title   = {On the existence of simple Liapunov functions for linear retarded difference-differential equations},
author = {Carvalho, Luis Antonio Vieira de and Infante, Ettore Hector Ferrari, and Walker, John Adrew},
year = {1980},
doi = {10.2748/tmj/1178229644},
journal   = {Tohoku Mathematical Journal}
}