Perhaps you should try some spelling variations:
hieu quan » hieu qua, lieu quan, thien quan
su triet » su viet, su tien, ve triet
danh vai » danh sai, danh va, doanh van
nang noi » nang doc
thu sach » thuat sach, thuoc sach, thu hoach
nang co » nang cao, nang doc, nang hoc
quan am » quan nam, quan tam, quan ao
thuc va » thuc vat, thuc dan, thuc day
va danh » va dinh, va dan, va hanh
tu sach » su sach, te sach, tu cach
vai su » va su, van su, lai su

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) OR (thu sach)) ty ((nang co) OR (nang noi)) hoi. hieu quan am thuc va danh vai su triet~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) OR (thu sach)) ty ((nang co) or (nang noi)) hoi. hieu quan am thuc va danh vai su triet~".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) OR (thu sach)) ty ((nang co) or (nang noi)) hoi. hieu quan am thuc va danh vai su triet*.