Arthashastra
व्यामिश्रो वा हस्ति रथ अश्वानां चक्र अन्तेषु हस्तिनः पार्श्वयोर् अश्वा रथा उरस्ये ॥
Alternatively , in a mixed formation of elephants, chariots, and horses, the elephants should be placed at the edges of the battle array, the horses on the flanks, and the chariots in the center.
english translation
vyAmizro vA hasti ratha azvAnAM cakra anteSu hastinaH pArzvayor azvA rathA urasye ॥
hk transliteration by Sanscript