Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
hieu van » hieu va, thien van, lieu va
van cham » van chat, van tham, va cham
han thai » han tai, ban thai, van thai
thai va » thai van
y nang » ly nang, v nang, may nang
luc va » duc va, tuc va
loc va » hoc 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: thu sach ((y nang) OR (ky nang)) xa hoi. hieu van cham ((luc va) or (loc va)) han thai va thiet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ((y nang) OR (ky nang)) xa hoi. hieu van cham ((luc va) OR (loc va)) han thai va thiet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ((y nang) OR (ky nang)) xa hoi. hieu van cham ((luc va) or (loc va)) han thai va thiet".
• Adding a wildcard symbol may retrieve word variants: thu sach ((y nang) OR (ky nang)) xa hoi. hieu van cham ((luc va) or (loc va)) han thai va thiet*.