$R_{h}$ and makes some of the functions strictly convex.
The authors then apply a classical dual based approach with Lagrange multiplier
-to solve such a problem~\cite{}.
+to solve such a problem~\cite{PM06}.
They first introduce dual variables
$u_{hi}$, $v_{h}$, $\lambda_{i}$, and $w_l$ for any
$h \in V$, $ i \in N$, and $l \in L$.
\delta_x \sum_{h \in V, l \in L } x_{hl}^2
+ \delta_r\sum_{h \in V }R_{h}^2
+ \delta_p\sum_{h \in V }P_{sh}^{\frac{8}{3}}.
-\label{eq:obj2}
+\label{eq:obj2p}
\end{equation}
In this equation we have first introduced new regularisation factors
(namely $\delta_x$, $\delta_r$, and $\delta_p$)
