Perhaps you should try some spelling variations:
phap thuc » phap thu, phap hoc, phap tu
toc sach » hoc sach, doc sach, thuoc sach
danh vai » danh sai, danh va, doanh van
va trien » va truyen, va thiet, va tuyen
lang ha » long ha
hieu ve » hieu van
sach ky » sac ky, sach y, sach ty
hieu va » lieu va, hieu qua
lang xa » dang xay, lang van
thuc va » thuc vat, thuc dan, thuc day
va danh » va dinh, va dan, va hanh
vai va » mai va, dai va, hai va

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

• Performing a fuzzy search may retrieve terms with similar spellings: toc sach ky ((lang xa) OR (lang ha)) hoi. ((hieu ve) or (hieu va)) phap thuc va danh vai va trien~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ky ((lang xa) OR (lang ha)) hoi. ((hieu ve) OR (hieu va)) phap thuc va danh vai va trien.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ky ((lang xa) OR (lang ha)) hoi. ((hieu ve) or (hieu va)) phap thuc va danh vai va trien".
• Adding a wildcard symbol may retrieve word variants: toc sach ky ((lang xa) OR (lang ha)) hoi. ((hieu ve) or (hieu va)) phap thuc va danh vai va trien*.