Perhaps you should try some spelling variations:
hieu van » thien van, lieu va, hieu ve
cam thuc » am thuc, nam thuc, cam thu
cau treo » cau theo, cau tren, cau triet
su sach » so sach, vu sach
hieu va » lieu va, hieu qua
hanh di » hanh vi, hang di, danh di
hanh de » hanh ve, hanh kem
y nang » ky nang, ly nang, v nang
x hoi » xa hoi, o hoi, x ho

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach y nang x hoi. ((hieu van) or (hieu va)) cam thuc vat ((hanh di) OR (hanh de)) cau treo~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach y nang x hoi. ((hieu van) OR (hieu va)) cam thuc vat ((hanh di) OR (hanh de)) cau treo.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach y nang x hoi. ((hieu van) or (hieu va)) cam thuc vat ((hanh di) OR (hanh de)) cau treo".
• Adding a wildcard symbol may retrieve word variants: su sach y nang x hoi. ((hieu van) or (hieu va)) cam thuc vat ((hanh di) OR (hanh de)) cau treo*.