Perhaps you should try some spelling variations:
thanh cau » thanh chau, thanh mau, nhanh cau
sach thi » sach tai, sach thieu, sach tham
sach thu » sach thue, sach thieu, sach tham
nam thuc » nam thuoc, am thuc, nam thu
thuc van » thuc vat, thuc dan, thuc va
van hanh » van thanh, ban hanh, van anh
hanh tai » thanh tai, hang tai, han tai
su triet » su viet, su tien, ve triet
qua nam » quan nam, cua nam, quang nam
tai su » tai so, tai tu, lai su

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 thu)) thanh cau hoi. hieu qua nam thuc van hanh tai su triet~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach thi) OR (sach thu)) thanh cau hoi. hieu qua nam thuc van hanh tai su triet".
• Adding a wildcard symbol may retrieve word variants: tu ((sach thi) OR (sach thu)) thanh cau hoi. hieu qua nam thuc van hanh tai su triet*.