PMO book or certification

I'd recommend the book 'The PMOSIG Program Management Office Handbook' published by J Ross Publishing. It was written by over 25 experts from around the world and across many sectors. It provides balanced insights and keys for all types of PMO. The content tends to focus mostly on program of work and project management offices with not so much on portfolio or enterprise PMO's. It's good though!
In terms of certification - AXELOS offer a basic certification but I would echo Dinahs' suggestion of exploring this site further.

Thanks for sharing this, Iain.

I have not found any PMO certifications yet. There are certifications related to governance which can be a big component of a PMO. PMO's can be very different in purpose. I would suggest look for articles and webinars on this site that will give you more input.

First of all, let me say that to have or not to have a PMO is related to organizational strategy and all related to that will help a lot. I meant, is more related to read books on business administration than to read books on project management. Second, as @Iain stated above the best work from years was AXELOS. I have the opportunity to participate on that work before the licences were bough by Axelos and at this time they were for free. I was not part of the certifications then I can not talk about that. But all related to PMO, Value Management, Maturity is consistent and reliable.

First of all, let me say that to have or not to have a PMO is related to organizational strategy and all related to that will help a lot. I meant, is more related to read books on business administration than to read books on project management. Second, as @Iain stated above the best work from years was AXELOS. I have the opportunity to participate on that work before the licences were bough by Axelos and at this time they were for free. I was not part of the certifications then I can not talk about that. But all related to PMO, Value Management, Maturity is consistent and reliable.