How to define generic class constructor in .cpp file, not .h file?

Question

I have generic class in .h file

#include "DictionaryListNode.h"

template<typename KeyType, typename ValueType>
class DictionaryList {
private:
    DictionaryListNode<KeyType, ValueType>* head;
public:
    DictionaryList();
};

I want to define its constructor in .cpp file

#include "DictionaryList.h"

template<typename KeyType, typename ValueType>
DictionaryList<KeyType, ValueType>::DictionaryList() {
    this->head = nullptr;
}

But I get error, which says nothing about problem

Undefined symbols for architecture arm64:
  "DictionaryList<int, int>::DictionaryList()", referenced from:
      _main in main.cpp.o
ld: symbol(s) not found for architecture arm64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
ninja: build stopped: subcommand failed.

I tried to compile it for x86, the problem is not in architecture arm64

When I try to define constructor inside class description in header file, it compiles successfully. Like this:

template<typename KeyType, typename ValueType>
class DictionaryList {
private:
    DictionaryListNode<KeyType, ValueType>* head;
public:
    DictionaryList() {
        
    }
};

So the problem is definitely in constructor in .cpp file.