Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
duc tren » duoc tren, duc tien, duc tre
dua tren » dung tren
tu sach » thu sach, su sach, tu cach
te sach » toc sach
nang xa » nang x, lang xa, nang ma
nam duc » nam duoc, pham duc, nam thuc
va lang » va nang, hoa lang
lang di » lang dai, hang di, lang du

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) or (te sach)) ky nang xa hoi. hieu van nam duc va lang di ((duc tren) OR (dua tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (te sach)) ky nang xa hoi. hieu van nam duc va lang di ((duc tren) OR (dua tren)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (te sach)) ky nang xa hoi. hieu van nam duc va lang di ((duc tren) OR (dua tren))".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (te sach)) ky nang xa hoi. hieu van nam duc va lang di ((duc tren) OR (dua tren))*.