S.L.Loni සථීති විද්යා නිබන්ධය - The Educational Publications Department Sri lanka 1970 - 407p 1 - 2023-11-01 Nat. Bib. No.: 0004886 Nat. Bib. Agency Control No.: LON Subjects--Topical Terms: Mathematics(AL) Universal Decimal Class. No.: 531