Perhaps you should try some spelling variations:
vat thanh » dat thanh, gat thanh, tat thanh
thu nang » thi nang, thu bang, tho nang
thu hang » thi hang, thuc hanh, thu huong
nam thuc » nam thuoc, am thuc, nam thu
so sach » so sanh, bo sach, co sach
qua nam » quan nam, cua nam, quang nam
lai cua » dai cua, hai cua, thai cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: so sach ((thu nang) or (thu hang)) xa hoi. hieu qua nam thuc vat thanh ((lai cua) OR (lai chau)) te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ((thu nang) OR (thu hang)) xa hoi. hieu qua nam thuc vat thanh ((lai cua) OR (lai chau)) te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach ((thu nang) or (thu hang)) xa hoi. hieu qua nam thuc vat thanh ((lai cua) OR (lai chau)) te".
• Adding a wildcard symbol may retrieve word variants: so sach ((thu nang) or (thu hang)) xa hoi. hieu qua nam thuc vat thanh ((lai cua) OR (lai chau)) te*.