Perhaps you should try some spelling variations:
thuat sach » thuat lanh, thuat san
cac nuoc » cap nuoc, dat nuoc, cua nuoc
dang hai » dang khai, hang hai, dung hai
mai hoi » mai khoi, dai hoi, lai hoi
hieu va » lieu va, hieu qua
va dang » van dang, va nang, va lang
hai cua » thai cua, dai cua, hoi cua
y nang » ky nang, ly nang, v nang
ma hoi » xa hoi, ma hoa, me hoi
cua te » cua tu

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

• Performing a fuzzy search may retrieve terms with similar spellings: thuat sach y nang ((ma hoi) or (mai hoi)). hieu va ((cac nuoc) OR (hoc nuoc)) va dang hai cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thuat sach y nang ((ma hoi) OR (mai hoi)). hieu va ((cac nuoc) OR (hoc nuoc)) va dang hai cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thuat sach y nang ((ma hoi) or (mai hoi)). hieu va ((cac nuoc) OR (hoc nuoc)) va dang hai cua te".
• Adding a wildcard symbol may retrieve word variants: thuat sach y nang ((ma hoi) or (mai hoi)). hieu va ((cac nuoc) OR (hoc nuoc)) va dang hai cua te*.