Perhaps you should try some spelling variations:
su sach » so sach, vu sach
k7 tang » ky tang, kho tang, 27 thang
hieu va » lieu va, hieu qua
truc va » thuc va, thuc vat, trung va
va hanh » van hanh, va thanh, va danh
hanh ve » hanh vi, hanh va, hanh kem
su viet » so viet
7 tang » 6 tang
va cau » van cau, va cac, va dau
ve su » va su

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach ((7 tang) or (k7 tang)) ((le hoi) or (ma hoa)). hieu va cau truc va hanh ve su viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ((7 tang) OR (k7 tang)) ((le hoi) OR (ma hoa)). hieu va cau truc va hanh ve su viet.
• Adding a wildcard symbol may retrieve word variants: su sach ((7 tang) or (k7 tang)) ((le hoi) or (ma hoa)). hieu va cau truc va hanh ve su viet*.