Perhaps you should try some spelling variations:
hoc sach » hoc cac, hoc anh
hieu van » thien van, lieu va, hieu ve
danh va » doanh va, hanh va, anh va
va danh » va dinh, va dan, va hanh
nang xa » nang x, lang xa, nang ma
hieu va » lieu va, hieu qua
cam thu » nam thu, cac thu, ca thu
va cua » va chua, via cua, ca cua
thu va » thuc va, thue va, tu va
v nang » va nang, vu nang, van nang
cua te » cua tu

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((hoc sach) OR (hoc sinh)) v nang xa hoi. ((hieu va) or (hieu van)) cam thu va danh va cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((hoc sach) OR (hoc sinh)) v nang xa hoi. ((hieu va) OR (hieu van)) cam thu va danh va cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((hoc sach) OR (hoc sinh)) v nang xa hoi. ((hieu va) or (hieu van)) cam thu va danh va cua te".
• Adding a wildcard symbol may retrieve word variants: ((hoc sach) OR (hoc sinh)) v nang xa hoi. ((hieu va) or (hieu van)) cam thu va danh va cua te*.