Perhaps you should try some spelling variations:
hang vien » hang dien, hang tien, hang viet
hieu van » hieu va, thien van, lieu va
tu sach » thu sach, su sach, te sach
hang vi » hang va, hanh vi, hang di
nam loc » nam lo, nam moc, nam soc
ky dang » ky nang, ky danh
ky lang » ky nang, ky tang, tay lang
cu tren » tu tren, dua tren
loc va » hoc va, luc 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 ((ky lang) OR (ky dang)) xa hoi. hieu van nam loc va ((hang vi) or (hang vien)) cu tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((ky lang) OR (ky dang)) xa hoi. hieu van nam loc va ((hang vi) OR (hang vien)) cu tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((ky lang) OR (ky dang)) xa hoi. hieu van nam loc va ((hang vi) or (hang vien)) cu tren".
• Adding a wildcard symbol may retrieve word variants: tu sach ((ky lang) OR (ky dang)) xa hoi. hieu van nam loc va ((hang vi) or (hang vien)) cu tren*.