Perhaps you should try some spelling variations:
doc sach » hoc sach, toc sach, nuoc sach
thuc dan » thuc hanh, thuc vat
viet cua » viec cua, viet ca, viet qua
nang ma » tang ma, sang ma, nang cao
va nham » va cham, va tham, va nha
thuc va » thuc vat, thuc day
cua tre » cua te, cuu tre, cua triet
y nang » ky nang, ly nang, v nang
ma hoi » mai hoi, xa hoi, ma hoa

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 ma hoi. lieu va nham ((thuc va) or (((thuc dan) OR (hoc dan)))) anh viet cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc sach y nang ma hoi. lieu va nham ((thuc va) OR (((thuc dan) OR (hoc dan)))) anh viet cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc sach y nang ma hoi. lieu va nham ((thuc va) or (((thuc dan) OR (hoc dan)))) anh viet cua tre".
• Adding a wildcard symbol may retrieve word variants: doc sach y nang ma hoi. lieu va nham ((thuc va) or (((thuc dan) OR (hoc dan)))) anh viet cua tre*.