Perhaps you should try some spelling variations:
sach nganh » sach ngan, sach tranh, cac nganh
khach han » khach hang, khach san, khac hau
vu khach » vu khanh, vu khac, vay khach
han doat » chan doan, nhan hoat, han dau
doat hon » dua hon, hoat ho, luat hon
su sach » so sach, vu sach
hoa hoi » khoa hoi, hoa doi, hoc hoi

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( su sach nganh ((hoa hoi) OR (hoa hoc)) đong luc ) or ( vu khach han doat hon đong luc ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( su sach nganh ((hoa hoi) OR (hoa hoc)) đong luc ) OR ( vu khach han doat hon đong luc )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( su sach nganh ((hoa hoi) OR (hoa hoc)) đong luc ) or ( vu khach han doat hon đong luc ))".
• Adding a wildcard symbol may retrieve word variants: (( su sach nganh ((hoa hoi) OR (hoa hoc)) đong luc ) or ( vu khach han doat hon đong luc ))*.