Perhaps you should try some spelling variations:
thien van » thi van
thanh hoa » thanh pho
hanh hai » thanh hai, nhanh hai, hang hai
su sach » so sach, vu sach
ky lang » ky nang, ky dang, tay lang
ky tang » ky nang, ky dang, kho tang
van bac » van ban, van bao, van hac
cua tre » cua te, cuu tre, cua triet

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 lang) OR (ky tang)) xa hoi. thien van bac duc va ((hanh hai) or (thanh hoa)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ((ky lang) OR (ky tang)) xa hoi. thien van bac duc va ((hanh hai) OR (thanh hoa)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ((ky lang) OR (ky tang)) xa hoi. thien van bac duc va ((hanh hai) or (thanh hoa)) cua tre".
• Adding a wildcard symbol may retrieve word variants: su sach ((ky lang) OR (ky tang)) xa hoi. thien van bac duc va ((hanh hai) or (thanh hoa)) cua tre*.