How to find DOI?

please help me with this article https://pubmed.ncbi.nlm.nih.gov/35062806/#affiliation-4
I didn′t find its DOI

Metabolism and disposition of naltrexone in man after oral and intravenous administration.

need your help to find out DOI of Metabolism and disposition of naltrexone in man after oral and intravenous administration (https://dmd.aspetjournals.org/content/9/4/369.long).

https://doi.org/10.1134/S1995080221030069
Please help in finding DOI

por favor ayudenme a encontrar el DOI de este articulo
https://pubmed.ncbi.nlm.nih.gov/20540230/
PMID: 20540230

What should I do if I have no DOI ?
I have just a link

If someone could help me with the doi of this article?
https://pubmed.ncbi.nlm.nih.gov/8290466/

https://www.amazon.com/Innovator ... usiness/dp/00620602

hallo can any one get the doi for this book or will be nice if anyone can get the book for me thanks

Hi please help me find this paper “The sampling theory of power
spectrum estimates. Unable to find its DOI anywhere on internet.

Dear All,

Please help to find this book - thank you very much

DOI: https://doi.org/10.4324/9781003244776

Authors：Nguyen Minh Quang; James Albright

Article link：http://dx.doi.org/10.4324/9781003244776

Article Source：Routledge。