Perhaps you should try some spelling variations:
thanh dai » thanh hai, thanh tai, thanh oai
thanh dat » thanh san, thanh hai, thanh van
doc sach » hoc sach, toc sach, nuoc sach
yun pang » yu pang, yun wang, dun nang
hieu van » hieu va, thien van, lieu va
van cac » van hac, van cau, van bac
cac xuc » cam xuc, cac nuoc, chat xuc
cua tuc » cua duc, cua tu, cua thuoc
xuc va » duc va, tuc va, luc va
y hang » ly hang, ty hang, yu hang
ca hoi » cau hoi, cua hoi, xa hoi

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

• Performing a fuzzy search may retrieve terms with similar spellings: doc sach ((y hang) or (yun pang)) ca hoi. hieu van cac xuc va ((thanh dai) or (thanh dat)) cua tuc~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc sach ((y hang) OR (yun pang)) ca hoi. hieu van cac xuc va ((thanh dai) OR (thanh dat)) cua tuc.
• Adding a wildcard symbol may retrieve word variants: doc sach ((y hang) or (yun pang)) ca hoi. hieu van cac xuc va ((thanh dai) or (thanh dat)) cua tuc*.