| @Book{Woollams1996, | |
| title = {A grammar of Karo Batak, Sumatra}, | |
| publisher = {Pacific Linguistics}, | |
| year = {1996}, | |
| author = {Geoff Woollams}, | |
| } | |
| @InBook{Woollams2004, | |
| chapter = {Karo Batak}, | |
| pages = {534-561}, | |
| title = {The Austronesian Languages of Asia and Madagascar}, | |
| publisher = {Taylor \& Francis Ltd}, | |
| year = {2004}, | |
| author = {Geoff Woollams}, | |
| editor = {Alexander Adelaar and Nikolaus P. Himmelmann}, | |
| } | |