Perhaps you should try some spelling variations:
hanh loai » thanh hoai, thanh loan, phan loai
manh hanh » xanh hanh, danh thanh, minh thanh
hieu van » hieu va, thien van, lieu va
van cham » van chat, van tham, va cham
cham duc » pham duc, cham soc, pham duy
duc manh » suc manh, duc anh, duc minh
vu sach » vu bach, su sach, vu khach
sach ty » sach y, sach tu, sach thu
ty nang » ky nang, ty xang, ty hang
co viet » so viet, o viet, hoc viet
x hoi » xa hoi, o hoi, x ho

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

• Performing a fuzzy search may retrieve terms with similar spellings: vu sach ty nang x hoi. hieu van cham duc manh hanh loai ((hoa viet) or (co viet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu sach ty nang x hoi. hieu van cham duc manh hanh loai ((hoa viet) OR (co viet)).
• Adding a wildcard symbol may retrieve word variants: vu sach ty nang x hoi. hieu van cham duc manh hanh loai ((hoa viet) or (co viet))*.