Perhaps you should try some spelling variations:
van thanh » ban thanh, van tuan
hanh gian » thanh gian, thanh giang, manh giang
thanh duc » thach duc, than duc, thinh duc
doc sach » hoc sach, toc sach, nuoc sach
van hanh » ban hanh, van anh, van ban
hieu van » hieu va, thien van, lieu va
te sach » toc sach
nang xa » nang x, lang xa, mang xa
duc van » duc va, duc tan, duc manh
nang ma » tang ma, sang ma, nang cao
xu tre » xu tri

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

• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (doc sach)) ky ((nang xa) OR (nang ma)) hoi. hieu van thanh duc van hanh gian xu tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((te sach) or (doc sach)) ky ((nang xa) OR (nang ma)) hoi. hieu van thanh duc van hanh gian xu tre~".
• Adding a wildcard symbol may retrieve word variants: ((te sach) or (doc sach)) ky ((nang xa) OR (nang ma)) hoi. hieu van thanh duc van hanh gian xu tre*.