Perhaps you should try some spelling variations:
doc sach » hoc sach, toc sach, nuoc sach
thuc day » thuc dan, thuc vat
tien cua » trien cua, tiep cua, dien cua
kien cua » khien cua, dien cua, bien cua
sach ky » sac ky, sach y, sach ty
thuc va » thuc vat, thuc dan
va tham » van tham, va cham, va thanh
hieu va » lieu va, hieu qua
nang xa » nang x, lang xa, nang ma

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