Arthashastra
हस्तिनाम् उरस्यं रथानां कक्षाव् अश्वानां पक्षाव् इति मध्य भेदी ॥
Elephants [are placed] at the chest, chariots at the sides, and horses on the wings. This [formation] is called "breaking the center."
english translation
hastinAm urasyaM rathAnAM kakSAv azvAnAM pakSAv iti madhya bhedI ॥
hk transliteration by Sanscript