Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
thanh ve » hanh ve, thanh va, thanh vien
hieu van » hieu va, thien van, lieu va
truc va » thuc va, thuc vat, trung va
van cam » van nam, van lam, van cau
sang ma » tang ma, sang tao, mang may
nang ma » tang ma, nang cao, mang may
cua tre » cua te, cuu tre, cua triet
ve cua » le cua, de cua, te cua

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 ma) OR (sang ma)) hoi. hieu van cam ((tuc xa) or (truc va)) thanh ve cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach y ((nang ma) OR (sang ma)) hoi. hieu van cam ((tuc xa) OR (truc va)) thanh ve cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach y ((nang ma) OR (sang ma)) hoi. hieu van cam ((tuc xa) or (truc va)) thanh ve cua tre".
• Adding a wildcard symbol may retrieve word variants: thu sach y ((nang ma) OR (sang ma)) hoi. hieu van cam ((tuc xa) or (truc va)) thanh ve cua tre*.