Perhaps you should try some spelling variations:
hoc sach » hoc sinh, hoc cac, hoc anh
hang doi » hang loi, huong doi, hang tai
hieu van » hieu va, thien van, lieu va
cau tren » cu tren, dau tren, ca tren
ky lang » ky nang, ky dang, ky tang
lang xa » lang ha, dang xay, lang van
so sanh » do sanh
cam thu » nam thu, cac thu, ca thu
hang di » hang vi, hang dien, hang dich
van cam » van nam, van lam, van cau
thu va » thuc va, thue va, tu va

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 (so sanh)) ky lang xa hoi. hieu van cam thu va ((hang di) OR (hang doi)) cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((hoc sach) OR (so sanh)) ky lang xa hoi. hieu van cam thu va ((hang di) OR (hang doi)) cau tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((hoc sach) or (so sanh)) ky lang xa hoi. hieu van cam thu va ((hang di) OR (hang doi)) cau tren".
• Adding a wildcard symbol may retrieve word variants: ((hoc sach) or (so sanh)) ky lang xa hoi. hieu van cam thu va ((hang di) OR (hang doi)) cau tren*.