1. CMB 2016 (vol 59 pp. 849)
 Nah, Kyeongah; RĂ¶st, Gergely

Stability Threshold for Scalar Linear Periodic Delay Differential Equations
We prove that for the linear scalar delay differential
equation
$$ \dot{x}(t) =  a(t)x(t) + b(t)x(t1) $$
with nonnegative periodic coefficients of period $P\gt 0$, the
stability threshold for the trivial solution is
$r:=\int_{0}^{P}
\left(b(t)a(t)
\right)\mathrm{d}t=0,$
assuming that $b(t+1)a(t)$ does not change its sign. By constructing
a class of explicit examples, we show the counterintuitive result
that in general, $r=0$ is not a stability threshold.
Keywords:delay differential equation, stability, periodic system Categories:34K20, 34K06 

2. CMB 1998 (vol 41 pp. 207)
 Philos, Ch. G.; Sficas, Y. G.

An oscillation criterion for first order linear delay differential equations
A new oscillation criterion is given for the delay differential
equation $x'(t)+p(t)x \left(t\tau(t)\right)=0$, where $p$, $\tau
\in \C \left([0,\infty),[0,\infty)\right)$ and the function
$T$ defined by $T(t)=t\tau(t)$, $t\ge 0$ is increasing and such
that $\lim_{t\to\infty}T(t)=\infty$. This criterion concerns the
case where $\liminf_{t\to\infty} \int_{T(t)}^{t}p(s)\,ds\le
\frac{1}{e}$.
Keywords:Delay differential equation, oscillation Category:34K15 
