Perhaps you should try some spelling variations:
cau tren » cu tren, dau tren, ca tren
su sach » so sach, vu sach
ky lang » ky nang, ky tang, tay lang
ky dang » ky nang, ky danh
cac tac » cac bac, cac dac, cac tai
cac toc » cac toi, cac nuoc, cac thoi
dau thi » cau thi, dan thi, dao thi
thi cau » thi chau, thi cu, thi cam
va dau » va dao

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 dang)) xa hoi. lieu va ((cac tac) or (cac toc)) va dau thi cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ((ky lang) OR (ky dang)) xa hoi. lieu va ((cac tac) OR (cac toc)) va dau thi cau tren.
• Adding a wildcard symbol may retrieve word variants: su sach ((ky lang) or (ky dang)) xa hoi. lieu va ((cac tac) or (cac toc)) va dau thi cau tren*.