Perhaps you should try some spelling variations:
nham thuc » nhan thuc, nam thuc, nham thu
vanh tai » van tai, hanh tai, anh tai
vanh dai » van dai, van dao, va dai
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
thuc va » thuc vat, thuc dan, thuc day
va nham » va cham, va tham, va nha
hieu va » lieu va, hieu qua
dang xa » dang xay, lang xa, dang ha
ky dang » ky nang, ky danh
cua tre » cua te, cuu tre, cua triet

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 dang xa hoi. hieu va nham thuc va ((((vanh dai) OR (lanh dao))) or (vanh tai)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky dang xa hoi. hieu va nham thuc va ((((vanh dai) OR (lanh dao))) OR (vanh tai)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky dang xa hoi. hieu va nham thuc va ((((vanh dai) OR (lanh dao))) or (vanh tai)) cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ky dang xa hoi. hieu va nham thuc va ((((vanh dai) OR (lanh dao))) or (vanh tai)) cua tre*.