diff --git a/dokka.gradle b/dokka.gradle
index 3b006a7..dea94a8 100644
--- a/dokka.gradle
+++ b/dokka.gradle
@@ -1,6 +1,4 @@
-dokka {
-    outputFormat = 'html'
-
+dokkaHtml {
     switch (true) {
         case project.hasProperty("DOKKA_PATH"):
             outputDirectory = project.property("DOKKA_PATH").toString()
@@ -10,33 +8,30 @@ dokka {
             break
     }
 
-    multiplatform {
-        global {
-            perPackageOption {
-                prefix = "dev.inmo"
-                skipDeprecated = true
-                includeNonPublic = true
-                reportUndocumented = true
-            }
+    dokkaSourceSets {
+        configureEach {
+            skipDeprecated.set(true)
+            includeNonPublic.set(true)
+            reportUndocumented.set(true)
 
             sourceLink {
-                path = "./"
-                url = "https://github.com/InsanusMokrassar/krontab/blob/master/"
-                lineSuffix = "#L"
+                localDirectory.set(file("./"))
+                remoteUrl.set(new URL("https://github.com/InsanusMokrassar/krontab/blob/master/"))
+                remoteLineSuffix.set("#L")
             }
         }
 
-        common {
-            targets = ["JVM", "JS"]
+        named("commonMain") {
             sourceRoot { path = "src/commonMain" }
         }
-        js {
-            targets = ["JS"]
-            sourceRoot { path = "src/jsMain" }
-        }
-        jvm {
-            targets = ["JVM"]
-            sourceRoot { path = "src/jvmMain" }
-        }
+
+//
+//        named("jsMain") {
+//            sourceRoot { path = "src/jsMain" }
+//        }
+//
+//        named("jvmMain") {
+//            sourceRoot { path = "src/jvmMain" }
+//        }
     }
 }
diff --git a/gradle.properties b/gradle.properties
index 9b086d5..83a5763 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -9,7 +9,7 @@ kotlin.incremental.multiplatform=true
 kotlin_version=1.4.20
 kotlin_coroutines_version=1.4.2
 
-dokka_version=0.10.1
+dokka_version=1.4.20
 
 klockVersion=2.0.1
 
diff --git a/src/commonMain/kotlin/dev/inmo/krontab/collection/CollectionKronScheduler.kt b/src/commonMain/kotlin/dev/inmo/krontab/collection/CollectionKronScheduler.kt
index e819d16..2c6ad20 100644
--- a/src/commonMain/kotlin/dev/inmo/krontab/collection/CollectionKronScheduler.kt
+++ b/src/commonMain/kotlin/dev/inmo/krontab/collection/CollectionKronScheduler.kt
@@ -3,29 +3,42 @@ package dev.inmo.krontab.collection
 import com.soywiz.klock.DateTime
 import dev.inmo.krontab.KronScheduler
 import dev.inmo.krontab.anyCronDateTime
+import dev.inmo.krontab.internal.*
 import dev.inmo.krontab.internal.CronDateTimeScheduler
+import dev.inmo.krontab.internal.merge
 import dev.inmo.krontab.internal.toNearDateTime
 
+/**
+ * This scheduler will be useful in case you want to unite several different [KronScheduler]s
+ */
 data class CollectionKronScheduler private constructor(
     internal val schedulers: MutableList<KronScheduler>
 ) : KronScheduler {
     internal constructor(schedulers: List<KronScheduler>) : this(schedulers.toMutableList())
     internal constructor() : this(mutableListOf())
 
+    /**
+     * Add [kronScheduler] into its [schedulers] list
+     *
+     * * When [kronScheduler] is [CronDateTimeScheduler] it will merge all [CronDateTimeScheduler]s from [schedulers] list
+     * and this [kronScheduler] using [merge] function
+     * * When [kronScheduler] is [CollectionKronScheduler] it this instance will include all [kronScheduler]
+     * [schedulers]
+     * * Otherwise [kronScheduler] will be added to [schedulers] list
+     */
     fun include(kronScheduler: KronScheduler) {
         when (kronScheduler) {
             is CronDateTimeScheduler -> {
-                val resultCronDateTimes = kronScheduler.cronDateTimes.toMutableList()
+                val resultCronDateTimes = mutableListOf(kronScheduler)
                 schedulers.removeAll {
                     if (it is CronDateTimeScheduler) {
-                        resultCronDateTimes.addAll(it.cronDateTimes)
-                        true
+                        resultCronDateTimes.add(it)
                     } else {
                         false
                     }
                 }
                 schedulers.add(
-                    CronDateTimeScheduler(resultCronDateTimes.distinct())
+                    merge(resultCronDateTimes)
                 )
             }
             is CollectionKronScheduler -> kronScheduler.schedulers.forEach {
diff --git a/src/commonMain/kotlin/dev/inmo/krontab/internal/CronDateTimeScheduler.kt b/src/commonMain/kotlin/dev/inmo/krontab/internal/CronDateTimeScheduler.kt
index c178620..5d83a3c 100644
--- a/src/commonMain/kotlin/dev/inmo/krontab/internal/CronDateTimeScheduler.kt
+++ b/src/commonMain/kotlin/dev/inmo/krontab/internal/CronDateTimeScheduler.kt
@@ -30,3 +30,11 @@ internal data class CronDateTimeScheduler internal constructor(
     }
 }
 
+/**
+ * @return New instance of [CronDateTimeScheduler] with all unique [CronDateTimeScheduler.cronDateTimes] of
+ * [kronDateTimeSchedulers] included
+ */
+@Suppress("NOTHING_TO_INLINE")
+internal inline fun merge(kronDateTimeSchedulers: List<CronDateTimeScheduler>) = CronDateTimeScheduler(
+    kronDateTimeSchedulers.flatMap { it.cronDateTimes }.distinct()
+)