Brihat Parashara Hora Shastra
भागीकृतं त्रिभिर्भक्तं लब्धं चेष्टाबलं त्विति । स्थानदिक्कालदृक्चेष्टानिसर्गोत्थं च षड्विधम् ॥ २५॥
The Rāśi, degrees and minutes so arrived should be converted into degrees, minutes etc. and divided by 3, which will denote the motional strength of the Grah. Thus there are six sources of strength, called Sthan Bal, Dig Bal, Kaal Bal, Drik Bal, Chesht Bal and Naisargika Bal.
english translation
bhAgIkRtaM tribhirbhaktaM labdhaM ceSTAbalaM tviti । sthAnadikkAladRkceSTAnisargotthaM ca SaDvidham ॥ 25॥
hk transliteration by Sanscript