$[$Students$]------<[$Checkouts$]>------[$Books$]------[$Authors$]$

$|$ PK: Student$\_$ID $|$ PK: Checkout$\_$ID $|$ PK: Book$\_$ID $|$ PK: Author$\_$ID

$|$ First$\_$Name $|$ Student$\_$ID $($FK$)|$ Title $|$ First$\_$Name

$|$ Last$\_$Name $|$ Book$\_$ID $($FK$)|$ Year $|$ Last$\_$Name

$|$ Student$\_$Type $|$ Check$\_$Out$\_$Date $|$ Cost $|$ Birth$\_$Year

$|$ Due$\_$Date

$|$ Check$\_$In$\_$Date what is the relationship between these please give answer clearly