There are two ways to cite in Chicago style:
Note: here we give examples based on the 16th edition of the Chicago Manual of Style. Check out Purdue OWL's website for help with the 17th edition.
...according to Abdou1
1. Name Surname, Title in italics (Place of publication: Publisher, Year), page number.
Surname, Name. Title in italics. Place of publication: Publisher, Year.
according to Koven 1
Name Surname, "Title of Article: Subtitle." Title of Journal in Italics volume, issue number no. (Year): page
Suzanne Koven, "Mom at Bedside, Appears Calm." The New England Journal of Medicine 370, no. 2 (2014): 104
Surname, Name. "Title of Article: Subtitle." Title of Journal in Italics volume, issue number no. (Year): pages
Koven, Suzanne. "Mom at Bedside, Appears Calm." The New England Journal of Medicine 370, no. 2 (2014): 104-105.
found in UNESCO website1
1. Name Surname, “Title of Web Page,” Publishing Organization , publication date and/or access date if available, URL.
1."UNESCO in Brief," UNESCO, accessed September 5, 2018, https://en.unesco.org/about-us/introducing-unesco
Name Surname. “Title of Web Page.” Publishing Organization. Publication date and/or Access date if available. URL.
"UNESCO in Brief." UNESCO. Accessed September 5, 2018. https://en.unesco.org/about-us/introducing-unesco
A primary source can take various forms, it could be an image, a video or manuscript. For each form you need to follow different rules in order to cite it. Check out Purdue OWL Chicago Style Guide to find out more.