Perhaps you should try some spelling variations:
thien van » thi van
cam thuc » am thuc, nam thuc, cam thu
hieu van » hieu va, lieu va, hieu ve
hanh di » hanh vi, hanh de, hang di
va hanh » van hanh, va thanh, va danh
thuc va » thuc vat, thuc dan, thuc day
sach ky » sach y, sach ty, sach kem
nang ma » tang ma, sang ma, nang cao
ma hoi » mai hoi, xa hoi, ma hoa
sac ky » cac ky, sai ky
di cua » dai cua, doi cua, de cua
cua te » cua tu

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 (sac ky)) nang ma hoi. ((hieu van) OR (thien van)) cam thuc va hanh di cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach ky) OR (sac ky)) nang ma hoi. ((hieu van) OR (thien van)) cam thuc va hanh di cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sach ky) or (sac ky)) nang ma hoi. ((hieu van) OR (thien van)) cam thuc va hanh di cua te".
• Adding a wildcard symbol may retrieve word variants: su ((sach ky) or (sac ky)) nang ma hoi. ((hieu van) OR (thien van)) cam thuc va hanh di cua te*.