\[f_{n}(\zeta,\overline{\zeta})=c_{n}(\zeta)c_{n}(\overline{\zeta})\operatorname%
{Ai}\left(\zeta\right)\operatorname{Bi}\left(\overline{\zeta}\right)+c_{n}(%
\zeta)d_{n}(\overline{\zeta})\operatorname{Ai}\left(\zeta\right)\operatorname{%
Bi}'\left(\overline{\zeta}\right)+d_{n}(\zeta)c_{n}(\overline{\zeta})%
\operatorname{Ai}'\left(\zeta\right)\operatorname{Bi}\left(\overline{\zeta}%
\right)+d_{n}(\zeta)d_{n}(\overline{\zeta})\operatorname{Ai}'\left(\zeta\right%
)\operatorname{Bi}'\left(\overline{\zeta}\right),\]