Perhaps you should try some spelling variations:
thien van » thi van
doc sach » hoc sach, toc sach, nuoc sach
dinh dai » dinh dat, sinh dai, dinh dao
nam thuc » nam thuoc, am thuc, nam thu
cham tuc » nham thuc, pham thuc, tham thuc
ky tang » ky nang, ky dang, kho tang
va dinh » van dinh, va kinh, va tinh
ky lang » ky nang, ky dang, tay 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: doc sach ((ky lang) OR (ky tang)) xa hoi. thien van ((cham tuc) or (nam thuc)) va dinh dai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc sach ((ky lang) OR (ky tang)) xa hoi. thien van ((cham tuc) OR (nam thuc)) va dinh dai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "doc sach ((ky lang) OR (ky tang)) xa hoi. thien van ((cham tuc) or (nam thuc)) va dinh dai cua tre".
• Adding a wildcard symbol may retrieve word variants: doc sach ((ky lang) OR (ky tang)) xa hoi. thien van ((cham tuc) or (nam thuc)) va dinh dai cua tre*.