Perhaps you should try some spelling variations:
truong cao » truong dai
doc sach » hoc sach, toc sach, nuoc sach
hang tai » hang va, dung tai
tu sach » thu sach, su sach, te sach
ky lang » ky nang, ky dang, ky tang
lang xa » lang ha, dang xay, lang van
han tai » nhan tai, van tai, toan tai
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: ((tu sach) or (doc sach)) ky lang xa hoi. lieu va cac truong cao ((han tai) OR (hang tai)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (doc sach)) ky lang xa hoi. lieu va cac truong cao ((han tai) OR (hang tai)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (doc sach)) ky lang xa hoi. lieu va cac truong cao ((han tai) OR (hang tai)) cua tre".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (doc sach)) ky lang xa hoi. lieu va cac truong cao ((han tai) OR (hang tai)) cua tre*.