Please recommend a serum that is good for whitening.

I have small dark spots around my eyes, and it's bothering me.

I only use retinol serum occasionally.

I've tried the Isoi Rose Serum and Goodal Green Tangerine Serum a while ago when they were really popular through word of mouth.

It didn't improve dramatically, so I've been using it on and off.

Please recommend an effective whitening serum.