Perhaps you should try some spelling variations:
tinh dieu » trinh dieu, tinh dien, vinh dieu
dieu tra » dieu tri, kiem tra, dieu cua
truc may » tren may, truc va
thuc may » thuc day, phuc may, thuc ma
tang hoa » hang hoa, tang ha, tang ho
tu sach » thu sach, te sach, tu cach
tra tre » tran tren, tran tri, tran tro
hieu he » hieu ve, hiem he, hieu le
ky tang » ky nang, ky dang, kho tang
su sach » so sach, vu sach
he nam » ha nam, nghe nam

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) or (su sach)) ky tang hoa hoc. hieu he nam ((thuc may) OR (truc may)) tinh dieu tra tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (su sach)) ky tang hoa hoc. hieu he nam ((thuc may) OR (truc may)) tinh dieu tra tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (su sach)) ky tang hoa hoc. hieu he nam ((thuc may) OR (truc may)) tinh dieu tra tre".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (su sach)) ky tang hoa hoc. hieu he nam ((thuc may) OR (truc may)) tinh dieu tra tre*.