Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
nam thuc » nam thuoc, am thuc, nam thu
sach ly » sach y, sach lo, sach ty
hanh va » hanh vi
va hanh » van hanh, va thanh, va danh
cam tuc » cam xuc, cam tu, dam thuc
su tien » su kien, su hien, tu tieng
hang ca » nang cao, hang tai, hang dau
hieu ve » hieu va, hieu van

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

• Performing a fuzzy search may retrieve terms with similar spellings: toc sach ly ((hang ca) or (hang va)) hoi. hieu ve ((cam tuc) OR (nam thuc)) va hanh va su tien~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ly ((hang ca) OR (hang va)) hoi. hieu ve ((cam tuc) OR (nam thuc)) va hanh va su tien.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ly ((hang ca) or (hang va)) hoi. hieu ve ((cam tuc) OR (nam thuc)) va hanh va su tien".
• Adding a wildcard symbol may retrieve word variants: toc sach ly ((hang ca) or (hang va)) hoi. hieu ve ((cam tuc) OR (nam thuc)) va hanh va su tien*.