Perhaps you should try some spelling variations:
pham thuc » phap thuc, pham chuc, nham thuc
ly quang » le quang, vu quang
va pham » van pham, va phat, va phap
va hanh » van hanh, va thanh, va danh
thuc va » thuc vat, thuc dan, thuc day
tu sach » thu sach, su sach, te sach
hieu va » lieu va, hieu qua
tai ha » thai ha, tai hai, tai nha
di va » dai va, doi va, di vat

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

• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((ly hang) OR (ly quang)) tai ha. hieu va pham thuc va hanh ((di va) OR (di vao)) triet~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((ly hang) or (ly quang)) tai ha. hieu va pham thuc va hanh ((di va) OR (di vao)) triet~".
• Adding a wildcard symbol may retrieve word variants: tu sach ((ly hang) or (ly quang)) tai ha. hieu va pham thuc va hanh ((di va) OR (di vao)) triet*.