Perhaps you should try some spelling variations:
nam thuc » nam thuoc, am thuc, nam thu
hieu cua » hieu qua, dieu cua, bieu cua
nang ma » tang ma, sang ma, nang cao
sach ky » sach y, sach ty, sach kem
thuc va » thuc vat, thuc dan, thuc day
tai cau » tai cao
tai cac » tai cuc
cua nam » cua tam, cua ngan, cua nhan
ma hoi » mai hoi, xa hoi, ma hoa
sac ky » cac ky, sai ky
va dau » va dao

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoc ((sach ky) OR (sac ky)) nang ma hoi. hieu cua nam thuc va dau ((tai cau) or (tai cac)) treo~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((sach ky) OR (sac ky)) nang ma hoi. hieu cua nam thuc va dau ((tai cau) OR (tai cac)) treo.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((sach ky) OR (sac ky)) nang ma hoi. hieu cua nam thuc va dau ((tai cau) or (tai cac)) treo".
• Adding a wildcard symbol may retrieve word variants: hoc ((sach ky) OR (sac ky)) nang ma hoi. hieu cua nam thuc va dau ((tai cau) or (tai cac)) treo*.