Perhaps you should try some spelling variations:
hoang van » hang va
dai tren » dat tren, dau tren, dan tren
thanh vi » hanh vi, thanh va, thanh ve
sach thu » sach thue, sach thieu, sach tham
lang van » dang van, tang van, giang van
duc gia » quoc gia
cau duc » cao duc, cau luc, chu duc
hieu ve » hieu va, hieu van
sach ty » sach y, sach tu, xach tay
ve cau » ke cau, va cau, ve cac
vi dai » si dai, li dai, vien dai

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: te ((sach ty) or (sach thu)) ((lang van) OR (hoang van)) hoi. hieu ve cau duc gia thanh vi dai tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te ((sach ty) OR (sach thu)) ((lang van) OR (hoang van)) hoi. hieu ve cau duc gia thanh vi dai tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te ((sach ty) or (sach thu)) ((lang van) OR (hoang van)) hoi. hieu ve cau duc gia thanh vi dai tren".
• Adding a wildcard symbol may retrieve word variants: te ((sach ty) or (sach thu)) ((lang van) OR (hoang van)) hoi. hieu ve cau duc gia thanh vi dai tren*.