Perhaps you should try some spelling variations:
hoang van » hang va
hoc sach » hoc sinh, hoc cac, hoc anh
nam thuc » nam thuoc, am thuc, nam thu
cau tren » cu tren, dau tren, ca tren
hieu va » lieu va, hieu qua
lang xa » lang ha, dang xay, lang van
vai cau » va cau, van cau, vai cac
va dan » va dao, va dau, va dap
ca dan » cac dan, ca dao
va nam » van nam, ha nam, va nay

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 y ((lang xa) or (hoang van)) hoi. hieu va nam thuc ((va dan) OR (ca dan)) vai cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc sach y ((lang xa) OR (hoang van)) hoi. hieu va nam thuc ((va dan) OR (ca dan)) vai cau tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc sach y ((lang xa) or (hoang van)) hoi. hieu va nam thuc ((va dan) OR (ca dan)) vai cau tren".
• Adding a wildcard symbol may retrieve word variants: hoc sach y ((lang xa) or (hoang van)) hoi. hieu va nam thuc ((va dan) OR (ca dan)) vai cau tren*.