Perhaps you should try some spelling variations:
thuc day » thuc dan, thuc vat
su sach » so sach, vu sach
danh vu » danh tu, anh vu, danh du
truc va » thuc va, thuc vat, trung va
qua cac » cua cac
sach 7 » sach y, sach 2
ma hoi » mai hoi, xa hoi, me hoi
7 tang » 6 tang
vu va » vu van, tu va, su va
thiet » thieu

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 7 tang ((ma hoi) OR (ma hoa)). hieu qua cac ((truc va) or (thuc day)) danh vu va thiet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach 7 tang ((ma hoi) OR (ma hoa)). hieu qua cac ((truc va) OR (thuc day)) danh vu va thiet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach 7 tang ((ma hoi) OR (ma hoa)). hieu qua cac ((truc va) or (thuc day)) danh vu va thiet".
• Adding a wildcard symbol may retrieve word variants: su sach 7 tang ((ma hoi) OR (ma hoa)). hieu qua cac ((truc va) or (thuc day)) danh vu va thiet*.