Perhaps you should try some spelling variations:
hien bach » vien bach, thien hach, hien hanh
hieu hien » bieu hien, dieu hien, chieu chien
thanh doi » thanh loi, thanh moi, thanh do
so sach » so sanh, bo sach, co sach
sach ty » sach y, sach tu, sach thu
ty nang » ky nang, ty xang, ty hang
nang xa » nang x, lang xa, nang ma
tuoc va » thuoc va, nuoc va, tuc va
duoc va » nuoc va, duoc ma, duong va
doi cua » dai cua, hoi cua
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: so sach ty nang xa hoi. hieu hien bach ((tuoc va) or (((duoc va) OR (duc va)))) thanh doi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ty nang xa hoi. hieu hien bach ((tuoc va) OR (((duoc va) OR (duc va)))) thanh doi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach ty nang xa hoi. hieu hien bach ((tuoc va) or (((duoc va) OR (duc va)))) thanh doi cua tre".
• Adding a wildcard symbol may retrieve word variants: so sach ty nang xa hoi. hieu hien bach ((tuoc va) or (((duoc va) OR (duc va)))) thanh doi cua tre*.