Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
cam thuc » nam thuc, cam thu, can thuc
hanh hai » thanh hai, nhanh hai, hang hai
tu sach » thu sach, te sach, tu cach
su sach » so sach, vu sach
nang xa » nang x, lang xa, nang ma
va hanh » van hanh, va thanh, va danh
hai cuu » hai cua, hai chu, hai cuc
cuu tre » cua tre, cau tren, cau treo

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

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