WHAT ARE THE THREE WEEKS
The three weeks (also known as Bein Hametzarim-between the days of distress) is a time period between the 17th of Tammuz, when the first breach was made of the walls of Jerusalem and the 9th of Av, exactly three weeks afterwards when the Bais Hamikdash was destroyed (ER1-29).
Laws and Customs of the Three WeeksThe Kinos in Depth with Rabbi Zev Leff
Simcha, Aveilus and the Bais Hamikdash - The Selected Speeches by R' Shimon Schwab zt"l
The 9th of Av: by Nishmas Chaim.
Tisha B'Av 5759: by Zvi Akiva Fleisher
Tish'oh be'Av: by Rabbi Eliezer Chrysler
Tish'oh be'Av: by Rabbi Heshy Grossman
Moadim U'Zmanim 5761
Moadim U'Zmanim 5762
From the Prophets - on the Haftara by Jacob Solomon
Tisha B'Av Selections - Meshech Chochma 5766: by Zvi Akva Fleisher