Perhaps you should try some spelling variations:
ban hanh » ban hang
cua viet » ca viet, hoa viet, cua vat
su sach » so sach, vu sach
hieu va » lieu va, hieu qua
cam tuc » cam xuc, cam tu, nam thuc
tuc ban » thuc ban, truc ban, tu ban
v tang » 6 tang, 7 tang, 9 tang
5 tang » 6 tang, 7 tang
ma hoi » mai hoi, xa hoi, ma hoa
va cam » va cham, va cac, va cao
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: su sach ((v tang) or (5 tang)) ma hoi. hieu va cam tuc ban hanh vi cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ((v tang) OR (5 tang)) ma hoi. hieu va cam tuc ban hanh vi cua viet.
• Adding a wildcard symbol may retrieve word variants: su sach ((v tang) or (5 tang)) ma hoi. hieu va cam tuc ban hanh vi cua viet*.