That's why, from 1993, Diana Ross is in the Guinness Book of World Records

In 1976, Ross was named the "Female Entertainer of the XX Century" by Billboard magazine.

In October1993, in London, Diana Ross was inducted in the GUINNESS BOOK OF WORLD RECORDS, as " THE MOST SUCCESSFUL FEMALE MUSIC ARTIST OF ALL TIME " in history, due to her success in the United States and United Kingdom for having more hits than any female artist in the charts with a career total of 150 hits , singles and albums .
Motown Records ( where Diana Ross was with in the 60's, 70's ), did not certify Motown’s artists record sales until the very late 70's. And even when record companies began certifiying their record sales, they weren't obligated to, unlike today, where you have Soundscan that automatically calculates both physical and digital sales. So, in the 80's with RCA Records, Diana Ross began to get certified, but they only certified a certain amount of her sales. So, the reason that you don't see her name in the top selling female artist on wikiepedia (which they make a note about her and certification), is because those listed of all time best sellers, have their sales certified and usually articles mention Diana Ross selling close to 200 million records, but all her sales aren't certified.
Her career as the lead singer of the Supremes yielded record sales close to the Beatles' in the 60's, but you wont see the sales certified, just mentioned by scholars.
In the U.S..A singles charts, Diana Ross has had 18 number one hits
Also,Diana Ross is the only FEMALE SINGER to have received 3 PLATINUM records for singles : “ Someday will be together “, 1969 ( but certified by RIIA in August 1997 ) –
“ I’m gonna make you love me “ , 1969 ( but certified by RIIA in August 1997 ) , and
“ Endless Love” ( certified by RIIA in October 1981) .
At the time, in USA, singles were certified platinum records for sales over 2 million copies).

2018 - Four of Diana Ross singles earned a silver certification in the UK, each passing 200,000 copies in sales. The singles were "You Can't Hurry Love" (with The Supremes, March 2018), "I'm Coming Out" ( September 2018),"Baby Love" (with The Supremes, November 2018)and "Endless Love" (with Lionel Richie, December 2018).

2019, “Voices Of Love “ (November 2019 ) was certified UK GOLD CD ( over 100.000 copies sold ) by BPI . The new remix of “The Boss 2019” has hit No.1 on Billboard’s Dance Club Songs Top 50 Chart. The success of “The Boss 2019” continues to illustrate the unprecedented star-power of Ms. Ross as a trailblazer and legend in the music industry.

On March 2020, Diana Ross has once again made music magic! Considered one of the most influential recording artists and iconic entertainers of all time (as Leading Lady of the Supremes followed by a stunning solo career, Diana Ross influenced generations of entertainers turning Motown Upsidedown ), Ms. Ross rewrote history once again.
Diana Ross adds her fourth consecutive remix at N° 1 ( in total, her eighth No. 1) on Billboard's Dance Club Songs chart, as "Love Hangover 2020" rises 2-1 on the survey dated March 28, 2020. The track, remixed by Eric Kupper and Ralphi Rosario (a previously completed mix by Frankie Knuckles was also promoted), is Ross' fourth consecutive straight remixed classic to reign supreme, after "The Boss 2019" (April 2019), "I'm Coming Out/Upside Down 2018" (August 2018) and "Ain't No Mountain High Enough 2017" (January 2018).
Always in 2020, Insider.com named The Supremes "the best-selling vocal group to date", after Ebony estimated The Supremes' record sales at 50 million in 1980 and Euronews reported total sales exceeding 100 million records in 2014.
This would make the group one of the best-selling music artists of all time.
And more, in 2020,“You Can’t Hurry Love“( March 2019 ) was certified UK GOLD single ( over 400.000 copies sold ) by BPI .“Love And Life- The Very Best Of Diana Ross“ CD was certified UK PLATINUM CD ( over 300.000 copies sold ) by BPI .On October, “I’m Coming Out “ was certified UK GOLD single ( over 400.000 copies sold ) by BPI .

Until 2023, in UK Diana Ross had 29 singles in the TOP 10 , 62 singles in the TOP 40 and in total 86 singles in the charts and 29 ALBUMS reached the TOP 40, 14 of those the TOP 10, and 5 albums reached the number 1 position of the charts .
In the UK , Diana Ross has a record of a TOP 10 in every one of the last six decades ( the last TOP 10 was “ Thank You “ album who reached the UK charts at position number 7 on November 18, 2021) and had a top 75 hit single at least once every year from 1964 to 1996 in the UK, a period of 33 consecutive years: an absolute record for any performer.
Also until 2023, BPI certified to Diana Ross 12 PLATINUM records ( for 6 albums, 4 multiple platinum-“One Woman” ( 1993) album, 2 singles), 19 GOLD records ( for 15 albums and 4 singles ) and 25 SILVER records ( for 16 albums and 9 singles) .