Gautama Dharmasūtra is a Sanskrit text and likely one of the oldest Hindu Dharmasutras (600-200 BCE), whose manuscripts have survived into the modern age.
From this source
There are two extant commentaries on Gautama Dharmasūtra by Maskarin and Haradatta:
Maskarin can be assigned to – 900–1000 CE and is therefore older than Haradatta, who also commented on Āpastamba.
It appears that Haradatta has made extensive use of Maskarin’s commentary, a usage that would amount to plagiarism if it was done today.
Are any English translations for those two commentaries available?
