most serious way to authenticate picasso work of art if no provenance?

Which is the most serious way to authenticate a Picasso work of art if no provenance ?
Thanks.

Only by a certified appraiser. There is no way around that

Do you know any specialist can do such work in the most professional way .
Thanks
Leo

That totally depends on your area
Sothebys may do an appraisal for free, but they don't guarantee their findings to be 100% accurate...

Thanks.
I prefer an individual expert and not an auciton house.
Any help?
Who might be the person for this job according to knowledge and experience if you should have to select an expert?

Well, unless you are going to fly in an expert, it would really help to know where you are located...

A local auction house or museum might be able to tell you who in their area is considered an expert in terms of picasso and painting authentification.
even your insurance company might have a list of trusted experts.

some research online goes a long way too.

Thanks for your reply.
No matter where I am located , can contact by internet any serious expert.
Which would be the three most serious experts in Picasso paintings for certificate a work signed by him not including into the list Claude Picasso neither Maya Picasso?
Thanks.
Leo

ENRIQUE MALLEN FRM SPAIN on-line picasso project