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 ty » sach y, sach tu, sach thu
thuc va » thuc vat, thuc dan, thuc day
dan ki » dan ky, dan ke, dan li
pan li » ban li, dan li, han li

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 ty ((nang xa) or (nang ma)) hoi. hieu van nam thuc va ((dan ki) or (pan li)) su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ty ((nang xa) OR (nang ma)) hoi. hieu van nam thuc va ((dan ki) OR (pan li)) su triet.
• Adding a wildcard symbol may retrieve word variants: thu sach ty ((nang xa) or (nang ma)) hoi. hieu van nam thuc va ((dan ki) or (pan li)) su triet*.