Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
nam thuc » nam thuoc, am thuc, nam thu
hieu van » hieu va, thien van, lieu va
su triet » su viet, su tien, ve triet
nang ma » tang ma, sang ma, nang cao
nang xa » nang x, lang xa, mang xa
sach tu » sach thu, cach tu, sach ty
thuc va » thuc vat, thuc dan, thuc day
dan ki » dan ky, dan li, dan khai
dan ke » dan ky, dan ve, ban ke

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 tu ((nang xa) or (nang ma)) hoi. hieu van nam thuc va ((dan ki) OR (dan ke)) su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach tu ((nang xa) OR (nang ma)) hoi. hieu van nam thuc va ((dan ki) OR (dan ke)) su triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach tu ((nang xa) or (nang ma)) hoi. hieu van nam thuc va ((dan ki) OR (dan ke)) su triet".
• Adding a wildcard symbol may retrieve word variants: thu sach tu ((nang xa) or (nang ma)) hoi. hieu van nam thuc va ((dan ki) OR (dan ke)) su triet*.