If you were a girl in the 80's/90's, you had these series:

>Sweet Valley High
>Sweet Valley Twins
>Babysitter’s Club
>The Treehouse Times
>The Fabulous Five
>The Forever Friends
>Friends 4 Ever
>The Girls of Canby Hall
>The Gymnasts
>The Party Line
>Penpals
>Roommates
>The Saddle Club
>Sleepover Friends