Perhaps you should try some spelling variations:
dao nuoc » dat nuoc, dau nuoc, dao nguoi
hieu van » hieu va, thien van, lieu va
thai cuu » thai cua, tai cuc, thi cuc
dau thai » dau thau, da thai, dao thai
dao cuoc » dao cuong, dao duc, va cuoc
tu sach » thu sach, te sach, tu cach
su sach » so sach, vu sach
nang xa » nang x, lang xa, nang ma
cuu tre » cua tre, cau tren, cau treo
y nang » ky nang, ly nang, v nang
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) or (su sach)) y nang xa hoi. hieu van ((dao nuoc) OR (dao cuoc)) va dau thai cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (su sach)) y nang xa hoi. hieu van ((dao nuoc) OR (dao cuoc)) va dau thai cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (su sach)) y nang xa hoi. hieu van ((dao nuoc) OR (dao cuoc)) va dau thai cuu tre".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (su sach)) y nang xa hoi. hieu van ((dao nuoc) OR (dao cuoc)) va dau thai cuu tre*.