Perhaps you should try some spelling variations:
thanh dai » thanh tai, thanh dat, thanh oai
thanh hai » thanh phan, thanh hoa, thanh san
su sach » so sach, vu sach
dua ban » dia ban, cua ban, qua ban
cua tre » cua te, cuu tre, cua triet
cam dua » ca dua, cay dua, chay dua
hieu va » lieu va, hieu qua
may hoi » may thoi, tay hoi, mai hoi
ky dang » ky nang, ky danh
ky mang » ky nang, ke mang, ky tang
va cam » va cham, va cac, va cao

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 ((ky mang) OR (ky dang)) may hoi. hieu va cam dua ban ((thanh dai) or (thanh hai)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ((ky mang) OR (ky dang)) may hoi. hieu va cam dua ban ((thanh dai) OR (thanh hai)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ((ky mang) OR (ky dang)) may hoi. hieu va cam dua ban ((thanh dai) or (thanh hai)) cua tre".
• Adding a wildcard symbol may retrieve word variants: su sach ((ky mang) OR (ky dang)) may hoi. hieu va cam dua ban ((thanh dai) or (thanh hai)) cua tre*.