Perhaps you should try some spelling variations:
dan thai » dang thai, dan than, ban thai
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
nang xa » nang x, lang xa, nang ma
van dat » van dau, dan dat, van dan
dan thi » dang thi, tran thi, dinh thi
cuu tre » cua tre, cau tren, cau treo

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ky nang xa hoi. hieu ((van dat) OR (van dao)) nuoc va ((dan thai) or (dan thi)) cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang xa hoi. hieu ((van dat) OR (van dao)) nuoc va ((dan thai) OR (dan thi)) cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang xa hoi. hieu ((van dat) OR (van dao)) nuoc va ((dan thai) or (dan thi)) cuu tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang xa hoi. hieu ((van dat) OR (van dao)) nuoc va ((dan thai) or (dan thi)) cuu tre*.