Perhaps you should try some spelling variations:
nam thuc » nam thuoc, am thuc, nam thu
su sach » so sach, vu sach
va viet » hoa viet, san viet, mai viet
thuc va » thuc vat, thuc dan, thuc day
hieu ve » hieu va, hieu van
co viet » so viet, o viet, hoc viet
ky tang » ky nang, ky dang, kho tang
ky sang » ky nang, ky dang, duy sang
ma hoi » mai hoi, xa hoi, ma hoa
va dan » ca dan, va dao, va dau
dan vi » doan vi, don vi, dan va
ve nam » he nam, va nam, le nam

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 sang) OR (ky tang)) ma hoi. hieu ve nam thuc va dan vi ((va viet) or (co viet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ((ky sang) OR (ky tang)) ma hoi. hieu ve nam thuc va dan vi ((va viet) OR (co viet))*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ((ky sang) OR (ky tang)) ma hoi. hieu ve nam thuc va dan vi ((va viet) or (co viet))*".