LOS ANGELES, Jan. 12 (UPI) -- Billie Lourd says late mom Carrie Fisher will live on in her head and her heart.
The 24-year-old actress paid tribute to Fisher with a throwback photo Wednesday on Instagram following the Star Wars icon's death in December.
"'If my life weren't funny then it would just be true and that is unacceptable,'" Lourd quoted her mom in the caption.
"Finding the funny might take a while but I learned from the best and her voice will forever be in my head and in my heart," she added.
Fisher died at age 60 on Dec. 27, and her mom, Singin' in the Rain star Debbie Reynolds, died at age 84 the next day. Death certificates for the actresses confirmed they died of cardiac arrest and a stroke, respectively, although Fisher's death remains under investigation.
"Receiving all your prayers and kind words over the past week has given me strength during a time I thought strength could not exist," Lourd wrote Jan. 2 on Instagram. "There are no words to express how much I will miss my Abadaba and my one and only Momby."
Lourd was spotted Monday in Los Angeles with Scream Queens co-star and rumored boyfriend Taylor Lautner following Fisher and Reynolds' memorial services last week. The actress held her mom's service Jan. 5 at Fisher's home in Beverly Hills.
"Billie wanted the people her mother loved to gather in that living room one last time," a source told People. "All the tributes circled back to Billie and how much Carrie loved her."