Brihat Parashara Hora Shastra
चरे व्युत्क्रमतो ग्राह्या दृग्योग्याः स्थिरभे क्रमात् । विषमे क्रमतो द्वन्द्वे राशयो व्युत्क्रमात् समे ॥ १८७॥
In the case of the Dual Rāśi, if it is odd, the counting is onwards and the order is backwards in case of an even Rāśi for the Rāśis, receiving a Drishti.
english translation
care vyutkramato grAhyA dRgyogyAH sthirabhe kramAt । viSame kramato dvandve rAzayo vyutkramAt same ॥ 187॥
hk transliteration by Sanscript