Perhaps you should try some spelling variations:
thien van » thi van
cau tren » cu tren, dau tren, ca tren
nang mai » nang ma, nang tai, lang mai
danh hai » dang hai, lanh hai, manh hai
hieu van » hieu va, lieu va, hieu ve
vuc nang » cuc nang, vu nang, chuc nang
mai hoi » mai khoi, dai hoi, lai hoi
so sach » so sanh, bo sach, co sach
cam tuc » cam xuc, cam tu, nam thuc
va danh » va dinh, va dan, va hanh
hai cau » hai chau, hai chu, hai hau
su sach » vu sach
tuc va » thuc va, truc va, tuc xa

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((su sach) or (so sach)) vuc nang mai hoi. ((hieu van) OR (thien van)) cam tuc va danh hai cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (so sach)) vuc nang mai hoi. ((hieu van) OR (thien van)) cam tuc va danh hai cau tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((su sach) or (so sach)) vuc nang mai hoi. ((hieu van) OR (thien van)) cam tuc va danh hai cau tren".
• Adding a wildcard symbol may retrieve word variants: ((su sach) or (so sach)) vuc nang mai hoi. ((hieu van) OR (thien van)) cam tuc va danh hai cau tren*.