Perhaps you should try some spelling variations:
thuoc sach » nuoc sach, thuat sach, thuoc sinh
hoc sach » hoc sinh, hoc cac, hoc anh
cua viet » ca viet, hoa viet, cua vat
tu hang » thu hang, tu hung, ty hang
tu hanh » du hanh, lu hanh, thuc hanh
hieu va » lieu va, hieu qua
cam tuc » cam xuc, cam tu, nam thuc
va hanh » van hanh, va thanh, va danh
va cam » va cham, va cac, va cao
tuc va » thuc va, truc va, tuc xa
vi cua » vai cua, di cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((hoc sach) or (thuoc sach)) ((tu hang) OR (tu hanh)) cau hoi. hieu va cam tuc va hanh vi cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((hoc sach) OR (thuoc sach)) ((tu hang) OR (tu hanh)) cau hoi. hieu va cam tuc va hanh vi cua viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((hoc sach) or (thuoc sach)) ((tu hang) OR (tu hanh)) cau hoi. hieu va cam tuc va hanh vi cua viet".
• Adding a wildcard symbol may retrieve word variants: ((hoc sach) or (thuoc sach)) ((tu hang) OR (tu hanh)) cau hoi. hieu va cam tuc va hanh vi cua viet*.