Perhaps you should try some spelling variations:
thien van » thi van
duc tren » duoc tren, dua tren, duc tien
nam thuc » nam thuoc, am thuc, nam thu
lang do » dang do, lang o, lang co
va lang » va nang, hoa lang
tu sach » thu sach, su sach, te sach
ky dang » ky nang, ky danh
ky lang » ky nang, ky tang, tay lang
nam duc » nam duoc, pham duc, nam buoc
do duc » dao duc, do 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 dang)) xa hoi. thien van ((nam duc) OR (nam thuc)) va lang do duc tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((ky lang) OR (ky dang)) xa hoi. thien van ((nam duc) OR (nam thuc)) va lang do duc tren*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((ky lang) or (ky dang)) xa hoi. thien van ((nam duc) OR (nam thuc)) va lang do duc tren*".