Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
dau tren » dau tien, dat tren, dau tieng
tu sach » thu sach, su sach, te sach
ky lang » ky nang, ky dang, tay lang
ky tang » ky nang, ky dang, kho tang
nam duc » nam duoc, pham duc, nam thuc
va hang » van hang, va nang, va lang
hang di » hang doi, hang vi, hang dien
du tren » dua tren, duc tren, tu tren

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