Perhaps you should try some spelling variations:
danh viet » anh viet, ninh viet, nang viet
doc sach » hoc sach, toc sach, nuoc sach
thuc day » thuc vat
thuc dan » thuc hanh, hoc dan, thuc vat
viet cua » viec cua, viet ca, viet qua
cao hoi » cau hoi, co hoi, cao hoc
va nham » va cham, va tham, va nha
cua tre » cua te, cuu tre, cua triet
y nang » ky nang, ly nang, v nang

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

• Performing a fuzzy search may retrieve terms with similar spellings: doc sach y nang cao hoi. lieu va nham ((thuc day) OR (thuc dan)) danh viet cua tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc sach y nang cao hoi. lieu va nham ((thuc day) OR (thuc dan)) danh viet cua tre".
• Adding a wildcard symbol may retrieve word variants: doc sach y nang cao hoi. lieu va nham ((thuc day) OR (thuc dan)) danh viet cua tre*.