Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
cua quoc » cua thuoc
cua nuoc » cua nguoi, cua thuoc, nha nuoc
thuc va » thuc vat, thuc dan, thuc day
va danh » va dinh, va dan, va hanh
danh vi » hanh vi, dinh vi, danh di
lang xa » lang ha, dang xay, lang van
ve cham » va cham, ve chat, vu cham
ve cam » ve cac, va cam, ve cai
y lang » o lang, _ lang, tay lang

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

• Performing a fuzzy search may retrieve terms with similar spellings: toc sach y lang xa hoi. hieu ((ve cam) or (ve cham)) thuc va danh vi ((cua quoc) or (cua nuoc))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach y lang xa hoi. hieu ((ve cam) OR (ve cham)) thuc va danh vi ((cua quoc) OR (cua nuoc)).
• Adding a wildcard symbol may retrieve word variants: toc sach y lang xa hoi. hieu ((ve cam) or (ve cham)) thuc va danh vi ((cua quoc) or (cua nuoc))*.