Perhaps you should try some spelling variations:
hieu quan » hieu qua, lieu quan, thien quan
nang noi » nang doc
danh vai » danh sai, danh va, doanh van
su triet » su viet, su tien, ve triet
tu sach » thu sach, su sach, te sach
sach ty » sach y, sach tu, sach thu
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
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 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 ty ((nang co) or (nang noi)) hoi. hieu quan am thuc va danh vai su triet*.