Perhaps you should try some spelling variations:
thuoc sach » hoc sach, nuoc sach, thuat sach
thien van » thi van
cac thuc » cach thuc, cac thu, can thuc
thuc va » thuc vat, thuc dan, thuc day
van cac » van hac, van cau, van bac
lang xa » lang ha, dang xay, lang van
ky lang » ky nang, ky dang, ky tang
cua tre » cua te, cuu tre, cua triet
dan di » danh di, dan da, dan li
dan de » dan den, dang de, van de

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((thu hoach) or (thuoc sach)) ky lang xa hoi. thien van cac thuc va ((dan di) OR (dan de)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((thu hoach) OR (thuoc sach)) ky lang xa hoi. thien van cac thuc va ((dan di) OR (dan de)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((thu hoach) or (thuoc sach)) ky lang xa hoi. thien van cac thuc va ((dan di) OR (dan de)) cua tre".
• Adding a wildcard symbol may retrieve word variants: ((thu hoach) or (thuoc sach)) ky lang xa hoi. thien van cac thuc va ((dan di) OR (dan de)) cua tre*.