Perhaps you should try some spelling variations:
hieu thien » hieu hien, chieu chien, dieu khien
thien hach » thien thanh, hien hanh
hach xuc » thach duc, hanh xu, cach xu
tu sach » thu sach, su sach, te sach
sach ty » sach y, sach tu, sach thu
ty nang » ky nang, ty xang, ty hang
chu tre » cho tre, chu tri, cuu tre
va chu » va che, va cau, va chi
x hoi » xa hoi, o hoi, 5 hoi

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 ty nang ((x hoi) OR (x ho)). hieu thien hach xuc ((va tinh) or (may tinh)) va chu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty nang ((x hoi) OR (x ho)). hieu thien hach xuc ((va tinh) OR (may tinh)) va chu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ty nang ((x hoi) OR (x ho)). hieu thien hach xuc ((va tinh) or (may tinh)) va chu tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ty nang ((x hoi) OR (x ho)). hieu thien hach xuc ((va tinh) or (may tinh)) va chu tre*.