Sound effects libraries offered via A Sound Effect generally don’t require attribution, but for certain freebie packs it is a requirement. If it’s specifically mentioned that attribution/credit is required, here are some examples of how this attribution can look:

• Includes sound effects from https://asoundeffect.com
• Sound effects provided by https://asoundeffect.com
• With sound effects from https://asoundeffect.com

A Sound Effect logo (1200x630px) • A Sound Effect logo (1500x1500px)

See the full EULA for libraries requiring attribution/credit here (opens in a new window)