Perhaps you should try some spelling variations:
khan thong » khap thong, khau thong, nhan thong
thuc cach » thuoc sach, truoc cach, thuc hanh
thuc bach » truc bach, thuoc sach, thuc hanh
vu khach » vu khanh, vu khac, vay khach
kho khan » khoa kham, khoa than
vu sach » vu bach, su sach
so sanh » do sanh

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: ((((vu sach) or (vu khach))) or (so sanh)) tri ((thuc bach) or (thuc cach)) kho khan thong~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((((vu sach) OR (vu khach))) OR (so sanh)) tri ((thuc bach) OR (thuc cach)) kho khan thong.
• Adding a wildcard symbol may retrieve word variants: ((((vu sach) or (vu khach))) or (so sanh)) tri ((thuc bach) or (thuc cach)) kho khan thong*.