https://dds.las.ac.cn/service/document?appId=a1vacbnPuv9qJRzJvdNXfsesj9JbIa6e&appKey=sPBA4vANLzjnW1k5eufEcc4k7dxfNraW&ts=1763029731785&signature=e2080f5a1de8314dcc70955d48ea4094&articleTitle=Topics+in+Combinatorial+Group+Theory&articleAuthor=Gilbert+Baumslag&publicationTitle=Topics+in+Combinatorial+Group+Theory&language=&publicationType=1&publishYear=1993&isn=9783764329211&publisher=Birkh%C3%A4user+Basel