Perhaps you should try some spelling variations:
thien van » thi van
nam thuc » nam thuoc, am thuc, nam thu
tu sach » thu sach, su sach, te sach
hang di » hang doi, hang vi, hang dien
va hang » van hang, va nang, va lang
nam luc » nang luc, nhan luc, nam duoc
ky dang » ky nang, ky danh
ky tang » ky nang, kho tang, ky trong
du tren » dua tren, dau tren, duc tren
di du » li du

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 tang) or (ky dang)) xa hoi. thien van ((nam luc) or (nam thuc)) va hang di du tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((ky tang) OR (ky dang)) xa hoi. thien van ((nam luc) OR (nam thuc)) va hang di du tren.
• Adding a wildcard symbol may retrieve word variants: tu sach ((ky tang) or (ky dang)) xa hoi. thien van ((nam luc) or (nam thuc)) va hang di du tren*.