Perhaps you should try some spelling variations:
nam thuc » nam thuoc, am thuc, nam thu
trinh di » trinh do, trinh dien, trinh dinh
tinh dai » trinh dai, tinh da, tinh hai
sach ky » sac ky, sach y, sach ty
tu sach » thu sach, su sach, te sach
cam tuc » cam xuc, cam tu, dam thuc
hieu ve » hieu va, hieu van
nang xa » nang x, lang xa, nang ma
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 nang xa hoi. hieu ve ((cam tuc) OR (nam thuc)) va ((tinh dai) or (trinh di)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang xa hoi. hieu ve ((cam tuc) OR (nam thuc)) va ((tinh dai) OR (trinh di)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang xa hoi. hieu ve ((cam tuc) OR (nam thuc)) va ((tinh dai) or (trinh di)) cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang xa hoi. hieu ve ((cam tuc) OR (nam thuc)) va ((tinh dai) or (trinh di)) cua tre*.