Route 44 - Pokemon Gold, Silver and Crystal Guide - IGN

Pokemon HeartGold and SoulSilver Johto Pokedex

Pokemon HeartGold and SoulSilver :: Special Pokemon Guide

Johto Route 30 - Bulbapedia, the community-driven Pokémon encyclopedia

Pokemon: Everything In The Johto Region Changed In HeartGold & SoulSilver

Johto Route 29 - Bulbapedia, the community-driven Pokémon encyclopedia

Johto Route 36 - Bulbapedia, the community-driven Pokémon encyclopedia

Pokemon Heart Gold Kanto 06: Route 25!

Pokemon HeartGold and SoulSilver :: Game Maps

Johto Route 47: Remaster ▻ Pokémon Heart Gold & Soul Silver

Here is a map I made with the location and info for all catchable Pokemon in X and Y. : r/pokemon