Perhaps you should try some spelling variations:
thuoc sach » hoc sach, nuoc sach, thuat sach
dau tieng » dau tien, cau tieng, day tieng
dat tren » dat trong, dua tren
hieu ve » hieu va, hieu van
cac tuc » cac toc, cac tu, cac tac
va hanh » van hanh, va thanh, va danh
hanh ve » hanh vi, hanh va, hanh kem
nang co » nang doc, nang noi, nang hoc
tuc va » thuc va, truc va, tuc xa
ve cac » va cac, vien cac

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

• If you are trying to use Boolean operators, they must be ALL CAPS: thuoc sach y ((nang co) OR (nang cao)) hoi. hieu ve cac tuc va hanh ve ((dau tieng) OR (dat tren))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thuoc sach y ((nang co) OR (nang cao)) hoi. hieu ve cac tuc va hanh ve ((dau tieng) or (dat tren))~".
• Adding a wildcard symbol may retrieve word variants: thuoc sach y ((nang co) OR (nang cao)) hoi. hieu ve cac tuc va hanh ve ((dau tieng) or (dat tren))*.