Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
hanh tai » thanh tai, hang tai, han tai
duc manh » suc manh, duc anh, duc minh
tu sach » thu sach, su sach, te sach
cam duc » cam xuc, cao duc, pham duc
van cam » van nam, van lam, van cau
ty hang » ly hang, ty xang, thi hang
ty lang » tay lang, ty xang, tu lang
cua tre » cua te, cuu tre, cua triet

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 ((ty lang) OR (ty hang)) xa hoi. hieu van cam duc manh ((thanh san) or (hanh tai)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((ty lang) OR (ty hang)) xa hoi. hieu van cam duc manh ((thanh san) OR (hanh tai)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((ty lang) OR (ty hang)) xa hoi. hieu van cam duc manh ((thanh san) or (hanh tai)) cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ((ty lang) OR (ty hang)) xa hoi. hieu van cam duc manh ((thanh san) or (hanh tai)) cua tre*.