In his Vergleichende Grammatik , published in 1833 , Lithuanian was included .
For the first time , scientifically Baltic languages were researched and compared with other Indo - European languages in the 19th century , when Franz Bopp in 1816 laid the ground for comparative linguistics .
In Franz Bopp 's Vergleichende Grammatik , published in 1833 , Lithuanian was included .
For the first time , scientifically Baltic languages were researched and compared with other Indo - European languages in the 19th century , when Franz Bopp in 1816 laid the ground for comparative linguistics .