diff --git a/desktopDomain/src/main/kotlin/com/intelligentbackpack/desktopdomain/entities/implementations/AbstractSchoolSupply.kt b/desktopDomain/src/main/kotlin/com/intelligentbackpack/desktopdomain/entities/implementations/AbstractSchoolSupply.kt
new file mode 100644
index 00000000..12c40c3e
--- /dev/null
+++ b/desktopDomain/src/main/kotlin/com/intelligentbackpack/desktopdomain/entities/implementations/AbstractSchoolSupply.kt
@@ -0,0 +1,69 @@
+package com.intelligentbackpack.desktopdomain.entities.implementations
+
+import com.intelligentbackpack.desktopdomain.entities.MutableSchoolSupply
+import com.intelligentbackpack.desktopdomain.entities.SchoolSupply
+import com.intelligentbackpack.desktopdomain.entities.SchoolSupplyType
+import com.intelligentbackpack.desktopdomain.entities.Subject
+import com.intelligentbackpack.desktopdomain.exception.ReplaceException
+import com.intelligentbackpack.desktopdomain.policies.ReplacePolicy
+import kotlin.jvm.Throws
+
+/**
+ * Abstract implementation of a school supply.
+ *
+ * @property type The type of the school supply.
+ * @property rfidCode The RFID code of the school supply.
+ * @property subjects The subjects of the school supply.
+ * @property replacedBy The school supplies that replace this one.
+ * @property replace The school supplies that this one replaces.
+ */
+abstract class AbstractSchoolSupply<T : SchoolSupply> : MutableSchoolSupply<T> {
+
+    /**
+     * The type of the school supply.
+     * @param type The type of the school supply.
+     * @param rfidCode The RFID code of the school supply.
+     * @param subjects The subjects of the school supply.
+     * @param replacedBy The school supplies that replace this one.
+     * @param replace The school supplies that this one replaces.
+     * @return The school supply with the given type.
+     */
+    protected abstract fun copy(
+        type: SchoolSupplyType = this.type,
+        rfidCode: String = this.rfidCode,
+        subjects: Set<Subject> = this.subjects,
+        replacedBy: Set<T> = this.replacedBy,
+        replace: Set<T> = this.replace,
+    ): MutableSchoolSupply<T>
+
+    /**
+     * Add the given school supply to the list of school supplies that replace this one.
+     * @param schoolSupply The school supply to add.
+     * @return The school supply with the given school supply added to the list of school supplies that replace this one.
+     * @throws ReplaceException If the school supply that replace doesn't respect the [ReplacePolicy].
+     */
+    @Throws(ReplaceException::class)
+    override fun addReplacedBy(schoolSupply: T): MutableSchoolSupply<T> {
+        if (ReplacePolicy.isValid(setOf(schoolSupply), setOf(this)))
+            return this.copy(replacedBy = replacedBy + schoolSupply)
+        else
+            throw ReplaceException()
+    }
+
+    /**
+     * Add the given school supply to the list of school supplies that this one replaces.
+     * @param schoolSupply The school supply to add.
+     * @return The school supply with the given school supply added to the list of school supplies that this one replaces.
+     * @throws ReplaceException If the school supply to replace doesn't respect the [ReplacePolicy].
+     */
+    @Throws(ReplaceException::class)
+    override fun addReplace(schoolSupply: T): MutableSchoolSupply<T> {
+        if (ReplacePolicy.isValid(setOf(this), setOf(schoolSupply)))
+            return this.copy(replace = replace + schoolSupply)
+        else
+            throw ReplaceException()
+    }
+
+    override fun addSubjects(subjects: Set<Subject>) =
+        this.copy(subjects = this.subjects + subjects)
+}
diff --git a/desktopDomain/src/main/kotlin/com/intelligentbackpack/desktopdomain/entities/implementations/BookCopyImpl.kt b/desktopDomain/src/main/kotlin/com/intelligentbackpack/desktopdomain/entities/implementations/BookCopyImpl.kt
new file mode 100644
index 00000000..c99e88f3
--- /dev/null
+++ b/desktopDomain/src/main/kotlin/com/intelligentbackpack/desktopdomain/entities/implementations/BookCopyImpl.kt
@@ -0,0 +1,71 @@
+package com.intelligentbackpack.desktopdomain.entities.implementations
+
+import com.intelligentbackpack.desktopdomain.entities.BookCopy
+import com.intelligentbackpack.desktopdomain.entities.SchoolSupplyType
+import com.intelligentbackpack.desktopdomain.entities.SchoolSupplyTypes
+import com.intelligentbackpack.desktopdomain.entities.Subject
+
+/**
+ * Implementation of a book copy.
+ *
+ * @property rfidCode The RFID code of the book copy.
+ * @property subjects The subjects of the book copy.
+ * @property isbn The ISBN of the book copy.
+ * @property title The title of the book copy.
+ * @property authors The authors of the book copy.
+ * @property replacedBy The book copies that replace this one.
+ * @property replace The book copies that this one replaces.
+ * @property type is automatically set to [SchoolSupplyTypes.BOOK].
+ */
+internal data class BookCopyImpl(
+    override val rfidCode: String,
+) : AbstractSchoolSupply<BookCopy>(), BookCopy {
+
+    override lateinit var subjects: Set<Subject>
+        private set
+    override lateinit var isbn: String
+        private set
+    override lateinit var title: String
+        private set
+    override lateinit var authors: List<String>
+        private set
+    override var replacedBy: Set<BookCopy> = setOf()
+        private set
+    override var replace: Set<BookCopy> = setOf()
+        private set
+
+    constructor(
+        rfidCode: String,
+        subjects: Set<Subject>,
+        isbn: String,
+        title: String,
+        authors: List<String>,
+        replacedBy: Set<BookCopy>,
+        replace: Set<BookCopy>
+    ) : this(rfidCode) {
+        this.subjects = subjects
+        this.isbn = isbn
+        this.title = title
+        this.authors = authors
+        this.replacedBy = replacedBy
+        this.replace = replace
+    }
+
+    override val type: SchoolSupplyType = SchoolSupplyTypes.BOOK
+    override fun copy(
+        type: SchoolSupplyType,
+        rfidCode: String,
+        subjects: Set<Subject>,
+        replacedBy: Set<BookCopy>,
+        replace: Set<BookCopy>
+    ): BookCopy =
+        BookCopyImpl(
+            rfidCode = rfidCode,
+            subjects = subjects,
+            isbn = isbn,
+            title = title,
+            authors = authors,
+            replacedBy = replacedBy,
+            replace = replace
+        )
+}
diff --git a/desktopDomain/src/main/kotlin/com/intelligentbackpack/desktopdomain/entities/implementations/GeneralSchoolSupplyImpl.kt b/desktopDomain/src/main/kotlin/com/intelligentbackpack/desktopdomain/entities/implementations/GeneralSchoolSupplyImpl.kt
new file mode 100644
index 00000000..7ac6eed3
--- /dev/null
+++ b/desktopDomain/src/main/kotlin/com/intelligentbackpack/desktopdomain/entities/implementations/GeneralSchoolSupplyImpl.kt
@@ -0,0 +1,61 @@
+package com.intelligentbackpack.desktopdomain.entities.implementations
+
+import com.intelligentbackpack.desktopdomain.entities.GeneralSchoolSupply
+import com.intelligentbackpack.desktopdomain.entities.SchoolSupplyType
+import com.intelligentbackpack.desktopdomain.entities.Subject
+
+/**
+ * Implementation of a general school supply.
+ *
+ * @property type The type of the school supply.
+ * @property rfidCode The RFID code of the school supply.
+ * @property description The description of the school supply.
+ * @property subjects The subjects of the school supply.
+ * @property replacedBy The school supplies that replace this one.
+ * @property replace The school supplies that this one replaces.
+ */
+internal data class GeneralSchoolSupplyImpl(
+    override val rfidCode: String
+) : AbstractSchoolSupply<GeneralSchoolSupply>(), GeneralSchoolSupply {
+
+    constructor(
+        type: SchoolSupplyType,
+        rfidCode: String,
+        description: String,
+        subjects: Set<Subject>,
+        replacedBy: Set<GeneralSchoolSupply>,
+        replace: Set<GeneralSchoolSupply>
+    ) : this(rfidCode) {
+        this.type = type
+        this.description = description
+        this.subjects = subjects
+        this.replacedBy = replacedBy
+        this.replace = replace
+    }
+
+    override lateinit var type: SchoolSupplyType
+        private set
+    override lateinit var description: String
+        private set
+    override lateinit var subjects: Set<Subject>
+        private set
+    override var replacedBy: Set<GeneralSchoolSupply> = setOf()
+        private set
+    override var replace: Set<GeneralSchoolSupply> = setOf()
+        private set
+
+    override fun copy(
+        type: SchoolSupplyType,
+        rfidCode: String,
+        subjects: Set<Subject>,
+        replacedBy: Set<GeneralSchoolSupply>,
+        replace: Set<GeneralSchoolSupply>
+    ): GeneralSchoolSupply = GeneralSchoolSupplyImpl(
+        type = type,
+        rfidCode = rfidCode,
+        description = description,
+        subjects = subjects,
+        replacedBy = replacedBy,
+        replace = replace
+    )
+}