Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
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 lang, va hanh
va nang » van nang, da nang, cam nang
du tren » dua tren, dau tren, duc tren
doi du » doi dau, doi deu, doi duy

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) OR (va nang)) doi du 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) OR (va nang)) doi du 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) OR (va nang)) doi du tren".
• Adding a wildcard symbol may retrieve word variants: tu sach ((ky lang) or (ky tang)) xa hoi. hieu van nam duc ((va hang) OR (va nang)) doi du tren*.