Perhaps you should try some spelling variations:
doc sach » toc sach, nuoc sach, dac sac
tinh dat » tinh da, dinh dat, tinh dau
hoc sach » hoc sinh, hoc cac, hoc anh
cau phuc » cau truc, chau phu, huu phuc
tu cach » tu cac
dat cua » dai cua, day cua, mat cua
va tinh » may tinh
phuc va » phuc vu, thuc va, chuc va
hieu ve » hieu va, hieu van
tang xa » trang xa, tang ma, lang xa
ky tang » ky nang, ky dang, kho tang
cua tre » cua te, cuu tre, cua triet
ve cau » ke cau, va cau, ve cac

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((tu cach) or (((doc sach) or (hoc sach)))) ky tang xa hoi. hieu ve cau phuc va tinh dat cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu cach) OR (((doc sach) OR (hoc sach)))) ky tang xa hoi. hieu ve cau phuc va tinh dat cua tre.
• Adding a wildcard symbol may retrieve word variants: ((tu cach) or (((doc sach) or (hoc sach)))) ky tang xa hoi. hieu ve cau phuc va tinh dat cua tre*.