Perhaps you should try some spelling variations:
sach thi » sach thu, sach thieu, sach tham
sach tai » sach bai, sach tham, sach dao
hieu van » hieu va, thien van, lieu va
nam thuc » nam thuoc, am thuc, nam thu
hanh xa » hanh va, hanh ma, hanh xu
thuc va » thuc vat, thuc dan, thuc day
va hanh » van hanh, va thanh, va danh
vai cua » hai cua, lai cua, bai cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu ((sach thi) or (sach tai)) hanh xa hoi. hieu van nam thuc va hanh ((vai cua) OR (dai cua)) triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach thi) OR (sach tai)) hanh xa hoi. hieu van nam thuc va hanh ((vai cua) OR (dai cua)) triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach thi) or (sach tai)) hanh xa hoi. hieu van nam thuc va hanh ((vai cua) OR (dai cua)) triet".
• Adding a wildcard symbol may retrieve word variants: tu ((sach thi) or (sach tai)) hanh xa hoi. hieu van nam thuc va hanh ((vai cua) OR (dai cua)) triet*.