Perhaps you should try some spelling variations:
va tinh » may tinh
va dinh » van dinh, va kinh, vu dinh
cam luc » cam xuc, cau luc
hieu va » lieu va, hieu qua
cua tre » cua te, cuu tre, cua triet
sach v » sach va, sach y, sach vay
sach 2 » sach y
di cua » dai cua, doi cua, de cua
va cam » va cham, va cac, va cao
x hoi » xa hoi, o hoi, x ho

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

• Performing a fuzzy search may retrieve terms with similar spellings: doc ((sach v) or (sach 2)) nang x hoi. hieu va cam luc ((va dinh) OR (va tinh)) di cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc ((sach v) OR (sach 2)) nang x hoi. hieu va cam luc ((va dinh) OR (va tinh)) di cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc ((sach v) or (sach 2)) nang x hoi. hieu va cam luc ((va dinh) OR (va tinh)) di cua tre".
• Adding a wildcard symbol may retrieve word variants: doc ((sach v) or (sach 2)) nang x hoi. hieu va cam luc ((va dinh) OR (va tinh)) di cua tre*.