Perhaps you should try some spelling variations:
pham thuc » phap thuc, pham chuc, nham thuc
cham truc » cau truc, nham thuc, nam truc
toc sach » hoc sach, doc sach, thuoc sach
hieu van » hieu va, thien van, lieu va
sinh dai » sinh thai, si dai, sinh vat
sach ky » sac ky, sach y, sach ty
va sinh » va kinh, va tinh, vi sinh
cua tre » cua te, cuu tre, cua triet
ma hoi » mai hoi, xa hoi, me hoi

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 ky nang ((ma hoi) or (ma hoa)). hieu van ((cham truc) OR (pham thuc)) va sinh dai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ky nang ((ma hoi) OR (ma hoa)). hieu van ((cham truc) OR (pham thuc)) va sinh dai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ky nang ((ma hoi) or (ma hoa)). hieu van ((cham truc) OR (pham thuc)) va sinh dai cua tre".
• Adding a wildcard symbol may retrieve word variants: toc sach ky nang ((ma hoi) or (ma hoa)). hieu van ((cham truc) OR (pham thuc)) va sinh dai cua tre*.