Perhaps you should try some spelling variations:
nang mai » nang ma, nang tai, lang mai
mai khoi » mai khoa, tai khoa, cac khoi
dinh vi » dinh ve, dinh viet, dinh tri
thuc va » thuc vat, thuc dan, thuc day
truc va » thuc vat, trung va
qua ca » qua cac, qua cua, qua cai
sach v » sach va, sach y, sach vay
sach 2 » sach y
vi va » vi van, vai va, vu va
thiet » thieu

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

• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach v) OR (sach 2)) nang mai khoi. hieu qua ca ((truc va) OR (thuc va)) dinh vi va thiet~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sach v) OR (sach 2)) nang mai khoi. hieu qua ca ((truc va) or (thuc va)) dinh vi va thiet~".
• Adding a wildcard symbol may retrieve word variants: su ((sach v) OR (sach 2)) nang mai khoi. hieu qua ca ((truc va) or (thuc va)) dinh vi va thiet*.