Perhaps you should try some spelling variations:
hoc truc » hoc thuc, hoc trung, hoc thuoc
su sach » so sach
vat cua » mat cua, bat cua, dat cua
va sinh » va kinh, va tinh, vi sinh
truc va » thuc va, thuc vat, trung va
hieu va » lieu va, hieu qua
cua tre » cua te, cuu tre, cua triet
hieu ve » hieu van
tang xa » trang xa, tang ma, lang xa
ky tang » ky nang, ky dang, kho tang
vu sach » vu bach, vu khach

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((su sach) or (vu sach)) ky tang xa hoi. ((hieu ve) or (hieu va)) hoc truc va sinh vat cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (vu sach)) ky tang xa hoi. ((hieu ve) OR (hieu va)) hoc truc va sinh vat cua tre.
• Adding a wildcard symbol may retrieve word variants: ((su sach) or (vu sach)) ky tang xa hoi. ((hieu ve) or (hieu va)) hoc truc va sinh vat cua tre*.