Perhaps you should try some spelling variations:
sach thu » sach thue, sach thieu, sach tham
thu nang » thi nang, thu hang, thu bang
pham duy » pham duc
doan van » doan va, hoang van, luan van
tu sach » thu sach, su sach, te sach
nang xa » nang x, lang xa, nang ma
hieu ve » hieu va, hieu van
ve pham » vi pham, v pham, ve phan
la tren » loai tren, dua tren, dat tren
duy va » duy vat, duy van, day va

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 thu nang xa hoi. hieu ve pham duy va ((doan van) or (doanh tai)) ((cau tao) or (la tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach thu nang xa hoi. hieu ve pham duy va ((doan van) OR (doanh tai)) ((cau tao) OR (la tren)).
• Adding a wildcard symbol may retrieve word variants: tu sach thu nang xa hoi. hieu ve pham duy va ((doan van) or (doanh tai)) ((cau tao) or (la tren))*.