Perhaps you should try some spelling variations:
nhieu viec » hieu viec, nhien viet
tiep tieng » tap tieng, tien tien, tiep trong
sach nuoc » sach duoc, cac nuoc, bach tuoc
su sach » so sach, vu sach
va hanh » van hanh, va thanh, va danh
hanh di » hanh vi, hanh de, hang di
cuu tre » cau tren, cau treo
cua tre » cua te, cua triet, dua tren
y nang » ky nang, ly nang, v nang
x hoi » xa hoi, o hoi, x ho

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach y nang x hoi. ((tiep tieng) or (nhieu viec)) sach nuoc va hanh di ((cuu tre) OR (cua tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach y nang x hoi. ((tiep tieng) OR (nhieu viec)) sach nuoc va hanh di ((cuu tre) OR (cua tre)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach y nang x hoi. ((tiep tieng) or (nhieu viec)) sach nuoc va hanh di ((cuu tre) OR (cua tre))".
• Adding a wildcard symbol may retrieve word variants: su sach y nang x hoi. ((tiep tieng) or (nhieu viec)) sach nuoc va hanh di ((cuu tre) OR (cua tre))*.