What are some of the constitutional amendments that have been made in relation to this article, according to the provided information?
Based on the provided context, there are several constitutional amendments that have been made in relation to this article:

1. The Constitution (Forty-second Amendment) Act, 1976, s. 15 and s. 16: These amendments were made on 3-1-1977 and included changes such as the addition of "Provided further that" clause in Article 81(5), adjustment of the date for readjustment to be based on the first census taken after the year 2026, and the power given to the President to specify a date for the readjustment to take effect.

2. The Constitution (Eighty-fourth Amendment) Act, 2001, s. 3 and s. 4: These amendments were made on 21-2-2002 and included changes such as the substitution of the words "the year 2000" with "the year 6 [2026]", and the substitution of certain words related to readjustment.

3. The Constitution (Eighty-seventh Amendment) Act, 2003, s. 2: This amendment was made on 22-6-2003 and included changes such as the substitution of "1991" with "the year 2001" concerning the census in Article 81(5)(i).