Perhaps you should try some spelling variations:
nam thuc » nam thuoc, am thuc, nam thu
va thanh » gia thanh, ban thanh, va tinh
hieu van » hieu va, thien van, lieu va
so sach » so sanh, bo sach, co sach
cam tuc » cam xuc, cam tu, dam thuc
lang xa » lang ha, dang xay, lang van
sach o » sach lo, sac o, sach y
o lang » hoa lang, hoi lang
ve tan » ve tac, ve ban, le tan
ve tai » te tai, de tai, le tai

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

• Performing a fuzzy search may retrieve terms with similar spellings: so sach o lang xa hoi. hieu van ((cam tuc) or (nam thuc)) va thanh ((ve tan) OR (ve tai)) trieu~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach o lang xa hoi. hieu van ((cam tuc) OR (nam thuc)) va thanh ((ve tan) OR (ve tai)) trieu*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach o lang xa hoi. hieu van ((cam tuc) or (nam thuc)) va thanh ((ve tan) OR (ve tai)) trieu*".