Arthashastra
एवम् ओजा दश विषम व्यूह प्रकृतयो भवन्ति ॥
Thus the added surplus of chariots should be one-third less (than the number added to the flanks and wings).
english translation
evam ojA daza viSama vyUha prakRtayo bhavanti ॥
hk transliteration by Sanscript