Perhaps you should try some spelling variations:
thuc dan » thuc hanh, hoc dan, thuc vat
duy sang » duy van, duy can, duy anh
sach duy » sach dung, sach duoc, sach dao
su sach » so sach, vu sach
dan dai » dat dai, can dai, dan dat
hieu ve » hieu va, hieu van
thuc va » thuc vat, thuc day
ve cam » ve cham, ve cac, va cam
ma hoi » mai hoi, ma hoa, me hoi
cua te » cua tu

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 duy sang ((ma hoi) OR (xa hoi)). hieu ve cam ((thuc va) OR (thuc dan)) dan dai cua te~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach duy sang ((ma hoi) OR (xa hoi)). hieu ve cam ((thuc va) or (thuc dan)) dan dai cua te~".
• Adding a wildcard symbol may retrieve word variants: su sach duy sang ((ma hoi) OR (xa hoi)). hieu ve cam ((thuc va) or (thuc dan)) dan dai cua te*.