Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, hieu ve
cam thuc » am thuc, nam thuc, cam thu
manh hai » lanh hai, minh hai, thanh hai
cau tren » cu tren, dau tren, ca tren
sach ky » sac ky, sach ty, sach kem
nang xa » nang x, lang xa, nang ma
thuc va » thuc vat, thuc dan, thuc day
va manh » van manh, va danh, va hanh
hai cau » hai chau, hai chu, hai hau

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 ky) or (sach y)) nang xa hoi. ((hieu van) OR (lieu va)) cam thuc va manh hai cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach ky) OR (sach y)) nang xa hoi. ((hieu van) OR (lieu va)) cam thuc va manh hai cau tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sach ky) or (sach y)) nang xa hoi. ((hieu van) OR (lieu va)) cam thuc va manh hai cau tren".
• Adding a wildcard symbol may retrieve word variants: su ((sach ky) or (sach y)) nang xa hoi. ((hieu van) OR (lieu va)) cam thuc va manh hai cau tren*.