Perhaps you should try some spelling variations:
thien van » thi van
hieu van » hieu va, lieu va, hieu ve
dao nuoc » dat nuoc, dao cuoc, dau nuoc
dau thai » dau thau, da thai, dao thai
thai cuu » thai cua, tai cuc, thi cuc
tu sach » thu sach, su sach, te sach
ky lang » ky nang, ky dang, tay lang
ky tang » ky nang, ky dang, kho tang
cuu tre » cua tre, cau tren, cau treo
va dau » va dao

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 lang) OR (ky tang)) xa hoi. ((hieu van) or (thien van)) dao nuoc va dau thai cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((ky lang) OR (ky tang)) xa hoi. ((hieu van) OR (thien van)) dao nuoc va dau thai cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((ky lang) OR (ky tang)) xa hoi. ((hieu van) or (thien van)) dao nuoc va dau thai cuu tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ((ky lang) OR (ky tang)) xa hoi. ((hieu van) or (thien van)) dao nuoc va dau thai cuu tre*.