Perhaps you should try some spelling variations:
pham thuc » phap thuc, pham chuc, nham thuc
cham tuc » nham thuc, tham thuc, cham soc
cua tre » cua te, cuu tre, cua triet
hieu ve » hieu va, hieu van
nang ma » tang ma, nang cao, mang may
sang ma » tang ma, sang tao, mang may
sac ky » cac ky, sai ky
va dan » ca dan, va dao, va dau
dan vi » doan vi, don vi, dan va
vi cua » vai cua, di cua
tu sac » tu sach, tu cac, tu san

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sac ky ((sang ma) or (nang ma)) hoi. hieu ve ((cham tuc) OR (pham thuc)) va dan vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sac ky ((sang ma) OR (nang ma)) hoi. hieu ve ((cham tuc) OR (pham thuc)) va dan vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sac ky ((sang ma) or (nang ma)) hoi. hieu ve ((cham tuc) OR (pham thuc)) va dan vi cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sac ky ((sang ma) or (nang ma)) hoi. hieu ve ((cham tuc) OR (pham thuc)) va dan vi cua tre*.