Perhaps you should try some spelling variations:
hieu quan » hieu qua, lieu quan, thien quan
hanh vien » thanh vien, hanh kien, thanh nien
thu sach » tu sach, thuat sach, thuoc sach
quan cau » quang cao, toan cau, quan ha
vien cac » vien bach, vien dai, vien da
ky lang » ky nang, ky tang, tay lang
ky dang » ky nang, ky danh
truc va » thuc va, trung va

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

• Performing a fuzzy search may retrieve terms with similar spellings: thu sach ((ky lang) or (ky dang)) xa hoi. hieu quan cau ((truc va) OR (thuc vat)) hanh vien cac tro~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ((ky lang) OR (ky dang)) xa hoi. hieu quan cau ((truc va) OR (thuc vat)) hanh vien cac tro.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ((ky lang) or (ky dang)) xa hoi. hieu quan cau ((truc va) OR (thuc vat)) hanh vien cac tro".
• Adding a wildcard symbol may retrieve word variants: thu sach ((ky lang) or (ky dang)) xa hoi. hieu quan cau ((truc va) OR (thuc vat)) hanh vien cac tro*.