Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
tham tuc » tham thuc, nham thuc, pham thuc
thai tuc » thai thuc, thai thuy, thai hoc
xac sinh » xac dinh, xa sinh, xuan sinh
sinh dai » sinh thai, si dai, sinh vat
ty nang » ty xang, ty hang, ly nang
cua tre » cua te, cuu tre, cua triet
ma hoi » mai hoi, xa hoi, ma hoa

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

• Performing a fuzzy search may retrieve terms with similar spellings: toc sach ((ty nang) OR (ky nang)) ma hoi. lieu va ((tham tuc) or (thai tuc)) xac sinh dai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ((ty nang) OR (ky nang)) ma hoi. lieu va ((tham tuc) OR (thai tuc)) xac sinh dai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ((ty nang) OR (ky nang)) ma hoi. lieu va ((tham tuc) or (thai tuc)) xac sinh dai cua tre".
• Adding a wildcard symbol may retrieve word variants: toc sach ((ty nang) OR (ky nang)) ma hoi. lieu va ((tham tuc) or (thai tuc)) xac sinh dai cua tre*.