Perhaps you should try some spelling variations:
van tham » van thanh, van tuan, van chat
nhan tai » hang tai, van tai, toan tai
tham soc » cham soc, tham nuoc, thai son
hieu van » hieu va, thien van, lieu va
han tai » hang tai, van tai, toan tai
sach ky » sac ky, sach y, sach ty
tu sach » thu sach, su sach, te sach
nang xa » nang x, lang xa, mang xa
nang ma » tang ma, sang ma, nang cao
soc va » hoc va, loc va, doc va
thiet » thieu

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ky ((nang xa) or (nang ma)) hoi. hieu van tham soc va ((han tai) or (nhan tai)) va thiet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky ((nang xa) OR (nang ma)) hoi. hieu van tham soc va ((han tai) OR (nhan tai)) va thiet.
• Adding a wildcard symbol may retrieve word variants: tu sach ky ((nang xa) or (nang ma)) hoi. hieu van tham soc va ((han tai) or (nhan tai)) va thiet*.