Perhaps you should try some spelling variations:
nang hoi » nang noi, nang hoc, nang ho
phan lai » phan loai, phan lap, phan lan
su triet » su viet, su tien, ve triet
tu sach » thu sach, su sach, te sach
sach tu » sach thu, cach tu, sach ty
tu nang » tru nang, tu nong, tu nano
hoi hoi » hoi hoc, hoc hoi, hoi doi
hieu su » hieu sau, tieu su, hieu so
hieu va » lieu va, hieu qua
truc va » thuc va, thuc vat, trung va
va phan » van phan, va phat, va phap

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach tu nang hoi hoi. ((hieu su) or (hieu va)) cau truc va phan lai su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach tu nang hoi hoi. ((hieu su) OR (hieu va)) cau truc va phan lai su triet.
• Adding a wildcard symbol may retrieve word variants: tu sach tu nang hoi hoi. ((hieu su) or (hieu va)) cau truc va phan lai su triet*.