Perhaps you should try some spelling variations:
tu sach » thu sach, su sach, tu cach
day cua » dai cua
dat cua » dai cua, mat cua, dan cua
hoc quy » hoc quan, hoc quoc
cac hoc » cach hoc, cac hop, bac hoc
hieu ve » hieu va, hieu van
tang xa » trang xa, tang ma, lang xa
ky tang » ky nang, ky dang, kho tang
te sach » toc sach
ve cac » va cac, vien cac

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 (te sach)) ky tang xa hoi. hieu ve cac hoc quy dinh ((dat cua) OR (day cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (te sach)) ky tang xa hoi. hieu ve cac hoc quy dinh ((dat cua) OR (day cua)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (te sach)) ky tang xa hoi. hieu ve cac hoc quy dinh ((dat cua) OR (day cua)) tre".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (te sach)) ky tang xa hoi. hieu ve cac hoc quy dinh ((dat cua) OR (day cua)) tre*.