Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
nam thuc » nam thuoc, am thuc, nam thu
vat danh » va danh, van danh, luat danh
vinh cuu » dinh cuu, sinh cua, dinh cu
tu sach » thu sach, su sach, te sach
lo lang » o lang, le lang, hoa lang
so lang » o lang, so dang, hoa lang
vi cuu » vi luu

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 ((lo lang) OR (so lang)) xa hoi. hieu van nam thuc vat danh ((vi cuu) or (vinh cuu)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((lo lang) OR (so lang)) xa hoi. hieu van nam thuc vat danh ((vi cuu) OR (vinh cuu)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((lo lang) OR (so lang)) xa hoi. hieu van nam thuc vat danh ((vi cuu) or (vinh cuu)) tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ((lo lang) OR (so lang)) xa hoi. hieu van nam thuc vat danh ((vi cuu) or (vinh cuu)) tre*.