▁ 1 9 3 0 ▁on , ▁publications ▁on ▁various ▁G be ▁languages ▁appeared ▁rapidly , ▁the ▁vast ▁majority ▁of ▁them ▁dealing ▁with ▁individual ▁G be ▁languages . ▁A ▁significant ▁exception ▁is ▁formed ▁by ▁the ▁extensive ▁compar ative ▁lingu istic ▁research ▁of ▁H oun k p ati ▁B ▁Christ ophe ▁Cap o , ▁which ▁resulted ▁in ▁an ▁internal ▁classification ▁of ▁the ▁G be ▁languages ▁and ▁a ▁reconst ruction ▁of ▁the ▁proto - G be ▁ph on ology . ▁Much ▁of ▁the ▁compar ative ▁research ▁for ▁Cap o ' s ▁classification ▁of ▁the ▁G be ▁languages ▁was ▁carried ▁out ▁in ▁the ▁ 1 9 7 0 s , ▁and ▁partial ▁results ▁were ▁published ▁in ▁the ▁late ▁ 1 9 7 0 s ▁and ▁early ▁ 1 9 8 0 s ▁in ▁the ▁form ▁of ▁articles ▁on ▁specific ▁ph on ological ▁develop ments ▁in ▁various ▁branches ▁of ▁G be ▁and , ▁not ably , ▁in ▁the ▁form ▁of ▁a ▁un ified ▁standard ▁orth ography ▁of ▁G be . ▁In ▁his ▁Renaissance ▁du ▁G be ▁( 1 9 8 8 ), ▁the ▁internal ▁classification ▁of ▁G be ▁was ▁published ▁in ▁full ▁for ▁the ▁first ▁time . ▁In ▁ 1 9 9 1 , ▁Cap o ▁published ▁a ▁compar ative ▁ph on ology ▁of ▁G be . ▁In ▁this ▁period , ▁Cap o ▁also ▁initi ated ▁Lab o ▁G be ▁( Int .), ▁the ▁' L abor atory ▁for ▁research ▁on ▁G be ▁languages ', ▁based ▁in ▁Ben in , ▁which ▁has ▁since ▁fost ered ▁research ▁and