Perhaps you should try some spelling variations:
doc sach » hoc sach, toc sach, nuoc sach
sach ky » sac ky, sach y, sach ty
hanh de » hanh ve, hanh kem
danh di » danh du, xanh di, danh dien
cua tre » cua te, cuu tre, cua triet
nang xa » nang x, lang xa, nang ma
va cao » va cac, va dao, va bao
va co » vo co

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 ky nang xa hoi. hieu ((va cao) OR (va co)) thuc vat ((danh di) or (hanh de)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc sach ky nang xa hoi. hieu ((va cao) OR (va co)) thuc vat ((danh di) OR (hanh de)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc sach ky nang xa hoi. hieu ((va cao) OR (va co)) thuc vat ((danh di) or (hanh de)) cua tre".
• Adding a wildcard symbol may retrieve word variants: doc sach ky nang xa hoi. hieu ((va cao) OR (va co)) thuc vat ((danh di) or (hanh de)) cua tre*.