Perhaps you should try some spelling variations:
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
nang xa » nang x, lang xa, nang ma
thuc va » thuc vat, thuc dan, thuc day
cua tre » cua te, cuu tre, cua triet
va cam » va cham, va cai, va cau
va cao » va co, va dao, va bao
va dan » ca dan, va dao, va dau
dan vi » doan vi, don vi, dan va
vi cua » vai cua, di cua

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

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